css 2026

CSS Snapshot 2026 W3C Group Note , 22 June 2026 More details about this document This version: https://www.w3.org/TR/2026/NOTE-css-2026-20260622/ Latest published version: https://www.w3.org/TR/css-2026/ Editor's Draft: https://drafts.csswg.org/css-2026/ Previous Versions: https://www.w3.org/TR/2026/NOTE-css-2026-20260326/ History: https://www.w3.org/standards/history/css-2026/ Feedback: CSSWG Issues Repository Editors: Tab Atkins Jr. ( Google ) Elika J. Etemad / fantasai ( Apple ) Florian Rivoal ( Invited Expert ) Chris Lilley ( W3C ) Sebastian Zartner ( Invited Expert ) Suggest an Edit for this Spec: GitHub Editor Copyright © 2026 World Wide Web Consortium . W3C ® liability , trademark and permissive document license rules apply. Abstract This document collects together into one definition all the specs that together form the current state of Cascading Style Sheets (CSS) as of 2026. The primary audience is CSS implementers, not CSS authors, as this definition includes modules by specification stability, not Web browser adoption rate. CSS is a language for describing the rendering of structured documents (such as HTML and XML) on screen, on paper, etc. Status of this document This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C standards and drafts index. This document was published by the CSS Working Group as a Group Note using the Note track . Group Notes are not endorsed by W3C nor its Members. Please send feedback by filing issues in GitHub (preferred), including the spec code “css-2026” in the title, like this: “[css-2026] …summary of comment… ”. All issues and comments are archived . Alternately, feedback can be sent to the ( archived ) public mailing list [email protected] . This document is governed by the 18 August 2025 W3C Process Document . The 15 September 2020 W3C Patent Policy does not carry any licensing requirements or commitments on this document. This document represents the state of CSS as of 2026. Table of Contents 1 Introduction 1.1 What is CSS? 1.2 Background: The W3C Process and CSS 2 Classification of CSS Specifications 2.1 Cascading Style Sheets (CSS) — The Official Definition 2.2 Reliable Candidate Recommendations 2.3 Fairly Stable Modules with limited implementation experience 2.4 Modules with Rough Interoperability 2.5 CSS Levels 2.6 CSS Profiles 3 Requirements for Responsible Implementation of CSS 3.1 Partial Implementations 3.2 Implementations of Unstable and Proprietary Features 3.2.1 Experimentation and Unstable Features 3.2.2 Proprietary and Non-standardized Features 3.2.3 Market Pressure and De Facto Standards 3.3 Implementations of CR-level Features 4 Safe to Release pre-CR Exceptions 5 The text/css media type 6 Security Considerations 7 Privacy Considerations 8 Indices 8.1 Terms Index 8.2 Selector Index 8.3 At-Rule Index 8.4 Property Index 8.5 Values Index 9 Acknowledgements Conformance Document conventions Conformance classes Partial implementations Implementations of Unstable and Proprietary Features Non-experimental implementations References Normative References Non-Normative References 1. Introduction When the first CSS specification was published, all of CSS was contained in one document that defined CSS Level 1. CSS Level 2 was defined also by a single, multi-chapter document. However for CSS beyond Level 2, the CSS Working Group chose to adopt a modular approach, where each module defines a part of CSS, rather than to define a single monolithic specification. This breaks the specification into more manageable chunks and allows more immediate, incremental improvement to CSS. Since different CSS modules are at different levels of stability, the CSS Working Group has chosen to publish this profile to define the current scope and state of Cascading Style Sheets as of 2026. 1.1. What is CSS? Cascading Style Sheets (CSS) CSS is a language for writing style sheets , and is designed to describe the rendering of structured documents (such as HTML and XML) on a variety of media. CSS is used to describe the presentation of a source document , and usually does not change the underlying semantics expressed by its document language . Style sheet A set of rules that specify the presentation of a document. Style sheets are written by an Author , and interpreted by a user agent , to present the document to the User . Source document The document to which one or more style sheets apply. A source document’s structure and semantics are encoded using a document language (e.g., HTML, XHTML, or SVG). Author An author is a person who writes documents and associated style sheets. An authoring tool is a user agent that generates style sheets. User A user is a person who interacts with a user agent to view, hear, or otherwise use the document. User agent (UA) A user agent is any program that interprets a document and its associated style sheets on behalf of a user . A user agent may display a document, read it aloud, cause it to be printed, convert it to another format, etc. For the purposes of the CSS specifications, a user agent is one that supports and interprets Cascading Style Sheets as defined in these specifications. 1.2. Background: The W3C Process and CSS This section is non-normative. In the W3C Process , a Recommendation-track document passes through three levels of stability, summarized below: Working Draft (WD) This is the design phase of a W3C spec. The WG iterates the spec in response to internal and external feedback. The first official Working Draft is designated the “First Public Working Draft” (FPWD). In the CSSWG, publishing FPWD indicates that the Working Group as a whole has agreed to work on the module, roughly as scoped out and proposed in the editor’s draft. The transition to the next stage is sometimes called “Last Call Working Draft” (LCWD) phase. The CSSWG transitions Working Drafts once we have resolved all known issues, and can make no further progress without feedback from building tests and implementations. This “Last Call for Comments” sets a deadline for reporting any outstanding issues, and requires the WG to specially track and address incoming feedback. The comment-tracking document is the Disposition of Comments (DoC). It is submitted along with an updated draft for the Director’s approval, to demonstrate wide review and acceptance. Candidate Recommendation (CR) This is the testing phase of a W3C spec. Notably, this phase is about using tests and implementations to test the specification: it is not about testing the implementations. This process often reveals more problems with the spec, and so a Candidate Recommendation will morph over time in response to implementation and testing feedback, though usually less so than during the design phase (WD). Demonstration of two correct, independent implementations of each feature is required to exit CR, so in this phase the WG builds a test suite and generates implementation reports. The transition to the next stage is “Proposed Recommendation” (PR). During this phase the W3C Advisory Committee must approve the transition to REC. Recommendation (REC) This is the completed state of a W3C spec and represents a maintenance phase. At this point the WG only maintains an errata document and occasionally publishes an updated edition that incorporates the errata back into the spec. An Editor’s Draft is effectively a live copy of the editors’ own working copy. It may or may not reflect Working Group consensus, and can at times be in a self-inconsistent state. (Because the publishing process at W3C is time-consuming and onerous, the Editor’s Draft is usually the best (most up-to-date) reference for a spec. Efforts are currently underway to reduce the friction of publishing, so that official drafts will be regularly up-to-date and Editor’s Drafts can return to their original function as scratch space.) 2. Classification of CSS Specifications A list of all CSS modules, stable and in-progress, and their statuses can be found at the CSS Current Work page . 2.1. Cascading Style Sheets (CSS) — The Official Definition This profile includes only specifications that we consider stable and for which we have enough implementation experience that we are sure of that stability. Note: This is not intended to be a CSS Desktop Browser Profile: inclusion in this profile is based on feature stability only and not on expected use or Web browser adoption. This profile defines CSS in its most complete form. As of 2026, Cascading Style Sheets (CSS) is defined by the following specifications. CSS Level 2, latest revision (including errata) [CSS2] This defines the core of CSS, parts of which are overridden by later specifications. We recommend in particular reading Chapter 2 , which introduces some of the basic concepts of CSS and its design principles. CSS Syntax Module Level 3 [CSS-SYNTAX-3] Replaces CSS2§4.1, CSS2§4.2, CSS2§4.4, and CSS2§G, redefining how CSS is parsed. CSS Style Attributes [CSS-STYLE-ATTR] Defines how CSS declarations can be embedded in markup attributes. Media Queries Level 3 [CSS3-MEDIAQUERIES] Replaces CSS2§7.3 and expands on the syntax for media-specific styles. CSS Conditional Rules Module Level 3 [CSS-CONDITIONAL-3] Extends and supersedes CSS2§7.2, updating the definition of @media rules to allow nesting and introducing the @supports rule for feature-support queries. Selectors Level 3 [SELECTORS-3] Replaces CSS2§5 and CSS2§6.4.3, defining an extended range of selectors. CSS Namespaces Module Level 3 [CSS3-NAMESPACE] Introduces an @namespace rule to allow namespace-prefixed selectors. CSS Cascading and Inheritance Level 4 [CSS-CASCADE-4] Extends and supersedes CSS2§1.4.3 and CSS2§6, as well as [CSS-CASCADE-3] . Describes how to collate style rules and assign values to all properties on all elements. By way of cascading and inheritance, values are propagated for all properties on all elements. CSS Values and Units Module Level 3 [CSS-VALUES-3] Extends and supersedes CSS2§1.4.2.1, CSS2§4.3, and CSS2§A.2.1–3, defining CSS’s property definition syntax and expanding its set of units. CSS Custom Properties for Cascading Variables Module Level 1 [CSS-VARIABLES-1] Introduces cascading variables as a new primitive value type that is accepted by all CSS properties, and custom properties for defining them. CSS Box Model Module Level 3 [CSS-BOX-3] Replaces CSS2§8.1, §8.2, §8.3 (but not §8.3.1), and §8.4. CSS Color Module Level 4 [CSS-COLOR-4] Extends and supersedes CSS2§4.3.6, CSS2§14.1, and CSS2§18.2, also extends and supersedes [CSS-COLOR-3] , introducing an extended range of color spaces beyond sRGB, extended color values, and CSS Object Model extensions for color. Also defines the opacity property. CSS Backgrounds and Borders Module Level 3 [CSS-BACKGROUNDS-3] Extends and supersedes CSS2§8.5 and CSS2§14.2, providing more control of backgrounds and borders, including layered background images, image borders, and drop shadows. CSS Images Module Level 3 [CSS-IMAGES-3] Redefines and incorporates the external 2D image value type, introduces native 2D gradients, and adds additional controls for replaced element sizing and rendering. CSS Fonts Module Level 3 [CSS-FONTS-3] Extends and supersedes CSS2§15 and provides more control over font choice and feature selection. CSS Writing Modes Level 3 [CSS-WRITING-MODES-3] Defines CSS support for various international writing modes, such as left-to-right (e.g. Latin or Indic), right-to-left (e.g. Hebrew or Arabic), bidirectional (e.g. mixed Latin and Arabic) and vertical (e.g. Asian scripts). Replaces and extends CSS2§8.6 and §9.10. CSS Multi-column Layout Module Level 1 [CSS-MULTICOL-1] Introduces multi-column flows to CSS layout. CSS Flexible Box Layout Module Level 1 [CSS-FLEXBOX-1] Introduces a flexible linear layout model for CSS. CSS Basic User Interface Module Level 3 [CSS-UI-3] Extends and supersedes CSS2§18.1 and CSS2§18.4, defining cursor , outline , and several new CSS features that also enhance the user interface. CSS Containment Module Level 1 [CSS-CONTAIN-1] Introduces the contain property, which enforces the independent CSS processing of an element’s subtree in order to enable heavy optimizations by user agents when used well. CSS Transforms Module Level 1 [CSS-TRANSFORMS-1] Introduces coordinate-based graphical transformations to CSS. Compositing and Blending Level 1 [COMPOSITING] Defines the compositing and blending of overlaid content and introduces features to control their modes. CSS Easing Functions Level 1 [CSS-EASING-1] . Describes a way for authors to define a transformation that controls the rate of change of some value. Applied to animations, such transformations can be used to produce animations that mimic physical phenomena such as momentum or to cause the animation to move in discrete steps producing robot-like movement. CSS Counter Styles Level 3 [CSS-COUNTER-STYLES-3] Introduces the @counter-style rule, which allows authors to define their own custom counter styles for use with CSS list-marker and generated-content counters [CSS-LISTS-3] . It also predefines a set of common counter styles, including the ones present in CSS2 and CSS2.1. Note: Although we don’t anticipate significant changes to the specifications that form this snapshot, their inclusion does not mean they are frozen. The Working Group will continue to address problems as they are found in these specs. Implementers should monitor www-style and/or the CSS Working Group Blog for any resulting changes, corrections, or clarifications. 2.2. Reliable Candidate Recommendations The following specifications are considered to be in a reliable state, meaning they have largely stable implementations and specifications, but are not yet at the Recommendation level due to minor issues or the need for additional implementation reports. Media Queries Level 4 [MEDIAQUERIES-4] Extends and supersedes [CSS3-MEDIAQUERIES] , expanding the syntax, deprecating most media types, and introducing new media features. CSS Scroll Snap Module Level 1 [CSS-SCROLL-SNAP-1] Contains features to control panning and scrolling behavior with “snap positions”. CSS Scrollbars Styling Module Level 1 [CSS-SCROLLBARS-1] Defines properties to influence the visual styling of scrollbars, introducing controls for their color and width. CSS Grid Layout Module Level 1 [CSS-GRID-1] Introduces a two-dimensional grid-based layout system, optimized for user interface design. In the grid layout model, the children of a grid container can be positioned into arbitrary slots in a predefined flexible or fixed-size layout grid. CSS Grid Layout Module Level 2 [CSS-GRID-2] Extends and supersedes [CSS-GRID-1] , introducing “subgrids” for managing nested markup in a shared grid framework. CSS Cascading and Inheritance Module Level 5 [CSS-CASCADE-5] Extends and supersedes [CSS-CASCADE-4] , introducing cascade layers which provide a structured way to organize and balance concerns within a single origin. CSS Color Adjustment Module Level 1 [CSS-COLOR-ADJUST-1] This module introduces a model and controls over automatic color adjustment by the user agent to handle user preferences and device output optimizations. CSS Conditional Rules Module Level 4 [CSS-CONDITIONAL-4] Extends [CSS-CONDITIONAL-3] to allow testing for supported selectors. 2.3. Fairly Stable Modules with limited implementation experience The following modules have completed design work, and are fairly stable, but have not received much testing and implementation experience yet. We hope to incorporate them into the official definition of CSS in a future snapshot. CSS Display Module Level 3 [CSS-DISPLAY-3] Replaces CSS2§9.1.2, §9.2.1 (but not §9.2.1.1), §9.2.2 (but not §9.2.2.1), §9.2.3, and §9.2.4 (and lays the foundations for replacing §9.7), defining how the CSS formatting box tree is generated from the document element tree and defining the display property that controls it. CSS Writing Modes Level 4 [CSS-WRITING-MODES-4] Extends and supersedes [CSS-WRITING-MODES-3] , adding more options for vertical writing. CSS Fragmentation Module Level 3 [CSS-BREAK-3] Describes the fragmentation model that partitions a flow into pages, columns, or regions and defines properties that control it. Extends and supersedes CSS2§13.3. CSS Box Alignment Module Level 3 [CSS-ALIGN-3] Introduces properties to control the alignment of boxes within their containers in the various CSS box layout models: block layout, table layout, flex layout, and grid layout. CSS Shapes Module Level 1 [CSS-SHAPES-1] Extends floats (CSS2§9.5) to effect non-rectangular wrapping shapes. CSS Text Module Level 3 [CSS-TEXT-3] Extends and supersedes CSS2§16 excepting §16.3, defining properties for text manipulation and specifying their processing model. It covers line breaking, justification and alignment, white space handling, and text transformation. CSS Text Decoration Module Level 3 [CSS-TEXT-DECOR-3] Extends and supersedes CSS2§16.3, providing more control over text decoration lines and adding the ability to specify text emphasis marks and text shadows. CSS Masking Module Level 1 [CSS-MASKING-1] Replaces CSS2§11.1.2 and introduces more powerful ways of clipping and masking content. CSS Speech Module Level 1 [CSS-SPEECH-1] Replaces CSS2§A, overhauling the (non-normative) speech rendering chapter. CSS View Transitions Module Level 1 [CSS-VIEW-TRANSITIONS-1] Defines the View Transition API, along with associated properties and pseudo-elements, which allows developers to create animated visual transitions representing changes in the document state. 2.4. Modules with Rough Interoperability Although the following modules have been widely deployed with rough interoperability , their details are not fully worked out or sufficiently well-specified and they need more testing and bugfixing. We hope to incorporate them into the official definition of CSS in a future snapshot. CSS Transitions [CSS-TRANSITIONS-1] and CSS Animations Level 1 [CSS-ANIMATIONS-1] . Introduces mechanisms for transitioning the computed values of CSS properties over time. CSS Will Change Module Level 1 [CSS-WILL-CHANGE-1] Introduces a performance hint property called will-change . Filter Effects Module Level 1 [FILTER-EFFECTS-1] Introduces filter effects as a way of processing an element’s rendering before it is displayed in the document. CSS Font Loading Module Level 3 [CSS-FONT-LOADING-3] Introduces events and interfaces used for dynamically loading font resources. CSS Box Sizing Module Level 3 [CSS-SIZING-3] Overlays and extends CSS§10., expanding the value set of the sizing properties, introducing more precise sizing terminology, and defining with more precision and detail various automatic sizing concepts only vaguely defined in CSS2. CSS Transforms Module Level 2 [CSS-TRANSFORMS-2] Builds upon [CSS-TRANSFORMS-1] to add new transform functions and properties for three-dimensional transforms, and convenience functions for simple transforms. CSS Lists and Counters Module Level 3 [CSS-LISTS-3] Contains CSS features related to list counters: styling them, positioning them, and manipulating their value. CSS Logical Properties and Values Level 1 [CSS-LOGICAL-1] Introduces logical properties and values that provide the author with the ability to control layout through logical, rather than physical, direction and dimension mappings. Also defines logical properties and values for the features defined in [CSS2] . These properties are writing-mode relative equivalents of their corresponding physical properties. CSS Positioned Layout Module Level 3 [CSS-POSITION-3] Contains defines coordinate-based positioning and offsetting schemes of CSS: relative positioning , sticky positioning , absolute positioning , and fixed positioning . Resize Observer [RESIZE-OBSERVER-1] This specification describes an API for observing changes to element’s principal box’s size. Web Animations [WEB-ANIMATIONS-1] Defines a model for synchronization and timing of changes to the presentation of a Web page. Also defines an application programming interface for interacting with this model. CSS Fonts Module Level 4 [CSS-FONTS-4] Extends and supersedes CSS Fonts 3 and provides more control over font choice and feature selection, including support for OpenType variations. Motion Path Module Level 1 [MOTION-1] This module allows authors to position any graphical object and animate it along an author specified path. CSS Scroll Anchoring Module Level 1 [CSS-SCROLL-ANCHORING-1] This module aims to minimize content shifts by locking the scroll position of a scroll container to a particular anchor element. CSS Object Model (CSSOM) [CSSOM-1] This module defines APIs for parsing, serializing, and manipulating CSS, Media Queries, and Selectors. CSS Color Module Level 5 [CSS-COLOR-5] Extends CSS Color 4 to add color spaces and color modification functions. Selectors Level 4 [SELECTORS-4] Extends Selectors Level 3 by introducing new pseudo-classes, pseudo-elements, and combinators, enhancing the ability to select elements based on more complex criteria and states. CSS Containment Module Level 2 [CSS-CONTAIN-2] Extends CSS Containment 1 to add style containment. CSSOM View Module [CSSOM-VIEW-1] This module defines APIs for querying and manipulating the visual viewport and layout viewport, as well as methods for scrolling elements into view. Geometry Interfaces Module Level 1 [GEOMETRY-1] This module defines basic basic geometric interfaces to represent points, rectangles, quadrilaterals, and transformation matrices. CSS Nesting Module Level 1 [CSS-NESTING-1] This module introduces the ability to nest one style rule inside another, with the selector of the child rule relative to the selector of the parent rule. This increases the modularity and maintainability of CSS stylesheets. 2.5. CSS Levels Cascading Style Sheets does not have versions in the traditional sense; instead it has levels . Each level of CSS builds on the previous, refining definitions and adding features. The feature set of each higher level is a superset of any lower level, and the behavior allowed for a given feature in a higher level is a subset of that allowed in the lower levels. A user agent conforming to a higher level of CSS is thus also conformant to all lower levels. CSS Level 1 The CSS Working Group considers the CSS1 specification to be obsolete. CSS Level 1 is defined as all the features defined in the CSS1 specification (properties, values, at-rules, etc), but using the syntax and definitions in the CSS2.1 specification . CSS Style Attributes defines its inclusion in element-specific style attributes. CSS Level 2 Although the CSS2 specification is technically a W3C Recommendation, it passed into the Recommendation stage before the W3C had defined the Candidate Recommendation stage. Over time implementation experience and further review has brought to light many problems in the CSS2 specification, so instead of expanding an already unwieldy errata list , the CSS Working Group chose to define CSS Level 2 Revision 1 (CSS2.1). In case of any conflict between the two specs CSS2.1 contains the definitive definition. Once CSS2.1 became Candidate Recommendation—effectively though not officially the same level of stability as CSS2—obsoleted the CSS2 Recommendation. Features in CSS2 that were dropped from CSS2.1 should be considered to be at the Candidate Recommendation stage, but note that many of these have been or will be pulled into a CSS Level 3 working draft, in which case that specification will, once it reaches CR, obsolete the definitions in CSS2. The CSS2.1 specification defines CSS Level 2 and the CSS Style Attributes specification defines its inclusion in element-specific style attributes. CSS Level 3 CSS Level 3 builds on CSS Level 2 module by module, using the CSS2.1 specification as its core. Each module adds functionality and/or replaces part of the CSS2.1 specification. The CSS Working Group intends that the new CSS modules will not contradict the CSS2.1 specification: only that they will add functionality and refine definitions. As each module is completed, it will be plugged in to the existing system of CSS2.1 plus previously-completed modules. From this level on modules are levelled independently: for example Selectors Level 4 may well be completed before CSS Line Module Level 3. Modules with no CSS Level 2 equivalent start at Level 1; modules that update features that existed in CSS Level 2 start at Level 3. CSS Level 4 and beyond There is no CSS Level 4. Independent modules can reach level 4 or beyond, but CSS the language no longer has levels. ("CSS Level 3" as a term is used only to differentiate it from the previous monolithic versions.) 2.6. CSS Profiles Not all implementations will implement all functionality defined in CSS. In the past, the Working Group published a few Profiles, which were meant to define the minimal subset of CSS that various classes of user agents were expected to support. This effort has been discontinued, as the Working Group was not finding it effective or useful, and the profiles previously defined are now unmaintained. Note: Partial implementations of CSS, even if that subset is an official profile, must follow the forward-compatible parsing rules for partial implementations . 3. Requirements for Responsible Implementation of CSS The following sections define several conformance requirements for implementing CSS responsibly, in a way that promotes interoperability in the present and future. 3.1. Partial Implementations So that authors can exploit the forward-compatible parsing rules to assign fallback values, CSS renderers must treat as invalid (and ignore as appropriate ) any at-rules, properties, property values, keywords, and other syntactic constructs for which they have no usable level of support . In particular, user agents must not selectively ignore unsupported property values and honor supported values in a single multi-value property declaration: if any value is considered invalid (as unsupported values must be), CSS requires that the entire declaration be ignored. 3.2. Implementations of Unstable and Proprietary Features To avoid clashes with future stable CSS features, the CSSWG recommends the following best practices for the implementation of unstable features and proprietary extensions to CSS: 3.2.1. Experimentation and Unstable Features Implementations of unstable features that are described in W3C specifications but are not interoperable should not be released broadly for general use; but may be released for limited, experimental use in controlled environments. Why? We want to allow both authors and implementors to experiment with the feature and give feedback, but prevent authors from relying on them in production websites and thereby accidentally "locking in" (through content dependence) certain syntax or behavior that might change later. For example, a UA could release an unstable features for experimentation through beta or other testing-stage builds; behind a hidden configuration flag; behind a switch enabled only for specific testing partners; or through some other means of limiting dependent use. A CSS feature is considered unstable until its specification has reached the Candidate Recommendation (CR) stage in the W3C process. In exceptional cases, the CSSWG may additionally, by an officially-recorded resolution, add pre-CR features to the set that are considered safe to release for broad use. See § 4 Safe to Release pre-CR Exceptions . Note: Vendors should consult the WG explicitly and not make assumptions on this point, as a pre-CR spec that hasn’t changed in awhile is usually more out-of-date than stable. 3.2.2. Proprietary and Non-standardized Features To avoid clashes with future CSS features, the CSS2.1 specification reserves a prefixed syntax [CSS2] for proprietary and experimental extensions to CSS. A CSS feature is a proprietary extension if it is meant for use in a closed environment accessible only to a single vendor’s user agent(s). A UA should support such proprietary extensions only through a vendor- prefixed syntax and not expose them to open (multi-UA) environments such as the World Wide Web. Why? The prefixing requirement allows shipping specialized features in closed environments without conflicting with future additions to standard CSS. The restriction on exposure to open systems is to prevent accidentally causing the public CSS environment to depend on an unstandardized proprietary extensions . For example, Firefox’s XUL-based UI, Apple’s iTunes UI, and Microsoft’s Universal Windows Platform app use extensions to CSS implemented by their respective UAs. So long as these UAs do not allow Web content to access these features, they do not provide an opportunity for such content to become dependent on their proprietary extensions . Even if a feature is intended to eventually be used in the Web, if it hasn’t yet been standardized it should still not be exposed to the Web. 3.2.3. Market Pressure and De Facto Standards If a feature is unstable (i.e. the spec has not yet stabilized), but at least three UAs implement the feature ( or a UA has broken the other rules and shipped for broad use an unstable or otherwise non-standard feature in a production release), and the implementations have rough interoperability, and the CSS Working Group has recorded consensus that this feature should exist and be released, implementers may ship that feature unprefixed in broad-release builds. Rough interoperability is satisfied by a subjective judgment that even though there may be differences, the implementations are sufficiently similar to be used in production websites for a substantial number of use cases. Note that the CSSWG must still be consulted to ensure coordination across vendors and to ensure coherency review by the CSS experts from each vendor. Note also that rough interoperability still usually means painful lack of interop in edge (or not-so-edge) cases, particularly because details have not been ironed out through the standards review process. Why? If a feature is sufficiently popular that three or more browsers have implemented it before it’s finished standardization, this clause allows releasing the pressure to ship. Also, if a feature has already escaped into the wild and sites have started depending on it, pretending it’s still “experimental” doesn’t help anyone. Allowing others to ship unprefixed recognizes that the feature is now de facto standardized and encourages authors to write cross-platform code. 3.2.3.1. Vendor-prefixing Unstable Features When exposing such a standards-track unstable feature to the Web in a production release, implementations should support both vendor-prefixed and unprefixed syntaxes for the feature. Once the feature has stabilized and the implementation is updated to match interoperable behavior, support for the vendor-prefixed syntax should be removed. Why? This is recommended so that authors can use the unprefixed syntax to target all implementations, but when necessary, can target specific implementations to work around incompatibilities among implementations as they get ironed out through the standards/bugfixing process. The lack of a phase where only the prefixed syntax is supported greatly reduces the risk of stylesheets being written with only the vendor-prefixed syntax. This in turn allows UA vendors to retire their prefixed syntax once the feature is stable, with a lower risk of breaking existing content. It also reduces the need occasionally felt by some vendors to support a feature with the prefix of another vendor, due to content depending on that syntax. Anyone promoting unstable features to authors should document them using their standard unprefixed syntax, and avoid encouraging the use of the vendor-prefixed syntax for any purpose other than working around implementation differences. 3.2.3.2. Preserving the Openness of CSS In order to preserve the open nature of CSS as a technology, vendors should make it possible for other implementors to freely implement any features that they do ship. To this end, they should provide spec-editing and testing resources to complete standardization of such features, and avoid other obstacles (e.g., platform dependency, licensing restrictions) to their competitors shipping the feature. 3.3. Implementations of CR-level Features Once a specification reaches the Candidate Recommendation stage, implementers should release an unprefixed implementation of any CR-level feature they can demonstrate to be correctly implemented according to spec, and should avoid exposing a prefixed variant of that feature. To establish and maintain the interoperability of CSS across implementations, the CSS Working Group requests that non-experimental CSS renderers submit an implementation report (and, if necessary, the testcases used for that implementation report) to the W3C before releasing an unprefixed implementation of any CSS features. Testcases submitted to W3C are subject to review and correction by the CSS Working Group. Up to date implementation reports for CSS specifications can be found on Web Platform Tests , which is maintained on GitHub . 4. Safe to Release pre-CR Exceptions The following features have been explicitly and proactively cleared by the CSS Working Group for broad release prior to the spec reaching Candidate Recommendation. See § 3.2.1 Experimentation and Unstable Features . The flow-relative equivalents of the sizing properties ( width , height , etc.), the border properties, the margin and padding properties. See explanation and specification . The min-content and max-content keywords of the sizing properties. See decision and specification . The conic-gradient() gradient notation. See decision . The aspect-ratio property. [CSS-SIZING-4] The translate , rotate , and scale properties. [CSS-TRANSFORMS-2] The hyphenate-character property. [CSS-TEXT-4] The color-mix() function. [CSS-COLOR-5] The <color-interpolation-method> , defined in [CSS-COLOR-4] and used for interpolation of linear, radial and conic gradients. [CSS-IMAGES-4] The relative color syntax, defined in [CSS-COLOR-5] The request url modifiers , defined in [CSS-VALUES-5] The display-modes , dynamic-range , scripting , prefers-reduced-motion , prefers-reduced-transparency , prefers-contrast , forced-colors , and prefers-color-scheme , media features, defined in [MEDIAQUERIES-5] The font-tech() and font-format() functions, defined in [CSS-CONDITIONAL-5] The :is() , :where() , and :has() pseudo-classes, and selector lists in :not() , defined in [SELECTORS-4] The text-decoration-thickness and text-underline-offset properties and the from-font value for text-underline-position , defined in [CSS-TEXT-DECOR-4] The ::marker pseudo-element , defined in [CSS-PSEUDO-4] The text-box-trim and text-box-edge properties including their text-box shorthand, defined in [CSS-INLINE-3] The env() function including the save-area-inset-* variables, defined in [CSS-ENV-1] The pseudo-classes :scope , :defined , :focus-within , :dir() , :any-link , :open , :popover-open , :modal , :fullscreen , :placeholder-shown , :default , :valid , :invalid , :required , :optional , and selector lists for the :nth-child() and :nth-last-child() pseudo-classes , defined in [SELECTORS-4] The accent-color property, the auto value for the outline-color property, and the <url-set> data type for the cursor property, defined in [CSS-UI-4] Everything in CSS Animations Level 1 and CSS Transitions Level 1 . 5. The text/css media type This updated registration obsoletes RFC 2318 . Type name: text

Subtype name: css

Required parameters: N/A

Optional parameters: charset (but see below)

Encoding considerations:

binary

Security considerations:

CSS is a modular specification and thus, the individual Security Considerations section of each CSS module in use should be consulted.

Interoperability considerations:

CSS has proven to be widely interoperable across computer platforms, across Web browsers of different makes, and for import and export in multiple authoring tools.

Published specification:

https://www.w3.org/TR/css

Applications that use this media type:

CSS is device-, platform- and vendor-neutral and is supported by a wide range of Web user agents and authoring tools for formatting HTML documents.

Fragment identifier considerations:

N/A

Additional information:

Deprecated alias names for this type: N/A Magic number(s): N/A File extension(s): .css macOS Uniform Type Identifier(s): public.css Windows clipboard name(s): N/A

Person & email address to contact for further information:

The W3C CSS Working Group <[email protected]>

Intended usage:

COMMON

Restrictions on usage:

N/A

Author: The W3C CSS Working Group

Change controller: W3C

Fallback encoding:

For Web compatibility, to determine the character encoding, user agents follow the CSS Syntax Level 3 specification, "To determine the fallback encoding of a stylesheet" https://www.w3.org/TR/css-syntax-3/#determine-the-fallback-encoding

Stylesheet authors should author their stylesheets in UTF-8, and ensure that either an HTTP header (or equivalent method) declares the encoding of the stylesheet to be UTF-8, or that the referring document declares its encoding to be UTF-8. 6. Security Considerations Please see the Security Considerations of the individual CSS modules. 7. Privacy Considerations Please see the Privacy Considerations of the individual CSS modules. 8. Indices These sections are non-normative. 8.1. Terms Index = in css2 in css2 ~= 1st <length> 2d matrix 2nd <length> 3d matrix 3d rendering context 3d transformed element 3d transform functions 3rd <length [0,∞]> 4th <length> absolute color absolute length absolute length unit absolutely position absolutely-positioned absolutely positioned box absolutely positioned element absolute position absolute-position containing block absolute positioning containing block absolute positioning layout absolute positioning layout model absolute scroll abstract dimensions accumulated 3d transformation matrix accumulation for one-based values activate view transition :active active-after boundary time activeborder activecaption active duration in css-animations-1 in web-animations-1 active interval active phase active (pseudo-class) active replace state active time active timeline active time space active view transition actual value actual values add a css style sheet additive color space additive tuple adjoining adjoining margins adjusted radius dimension advance measure :after in css2 in css2 after after-change style after phase aliceblue aligned subtree alignment baseline alignment container alignment context alignment subject 'all' media group alphabetic baseline alpha channel alpha component <alphavalue> alternate alternate flag alternate-reverse ambiguous image url analogous components analogous set an+b ancestor anchor anchor node anchor node selection algorithm anchor priority candidate anchor unit <angle> animatable animation animation class animation composite order animation direction animation effect animation events animation frame animation model animation origin animation playback events animation property name to idl attribute name animation-tainted animation time to origin-relative time animation time to timeline time animation type anonymous in css-display-3, for CSS in css2 anonymous box anonymous inline boxes antiquewhite apply any pending playback rate apply to appworkspace aqua aquamarine are a valid escape aspect value associated animation associated css style sheet associated document associated effect associated effect end associated with an animation associated with a timeline at-keyword atomic inline atomic inline box atomic inline-level box atomic inline-level boxes at-rule at-rules attr() attribute attribute selector 'audio' media group auditory icon augmented grid aural box model author authoring tool author origin author-origin author presentational hint origin author style sheet automatic block size automatic column position automatic grid position automatic inline size automatic minimum size automatic numbering automatic placement automatic position automatic row position automatic size auto-placement auto-placement cursor available block space available font faces available grid space available inline space available space avoid break values axis-lock axis value azure backdrop background background color background image background image layer background painting area background positioning area backslash escapes backwards baseline baseline alignment baseline alignment preference baseline content-alignment baseline self-alignment baseline set baseline-sharing group baseline table base size bearing angle :before in css2 in css2 before before-active boundary time before-change style before flag before phase beginning edges behave as auto behaves as auto behaving as auto beige bfc bidi formatting characters bidi-isolate bidi-isolated bidi isolation bidi paragraph bidirectionality bidirectionality (bidi) binary search gamut map with local minde bi-orientational bi-orientational transform bisque 'bitmap' media group black blanchedalmond ()-block []-block block {}-block block at-rule block axis block-axis block box block boxes block container block container box block dimension block end block-end block flow direction block formatting context block formatting context root blockification blockify block layout block-level block-level box block-level boxes block-level content block-level element block-level elements block scripts block size block-size block start block-start blue blueviolet blur radius boolean context border border area border box border color border edge border image border image area border image region border (of a box) border::of a box border properties border radius <border-style> border style border width both bottom box box alignment properties box::border box::content box::content height box::content width box-corner box edge box fragment box::margin box::overflow box::padding box tree break broadcast active observations broadcast active resize observations brown burlywood buttonface buttonhighlight buttons buttonshadow buttontext by computed value cadetblue calculate a color-mix() calculate box size calculate depth for node calibrated call the update callback can be displayed cancel cancel an animation cancel event candidate examination algorithm canonical unit can't be displayed canvas canvas background canvas surface captiontext captured element captured in a view transition capture rendering characteristics captures snap positions capture the image capture the new state capture the old state capturing the image caret node caret offset caret position carried forward cascade cascade-dependent keyword cascaded value cascade layers cascade origin case-sensitive flag cast a ray central baseline change the preferred css style sheet set name character character encoding characterized character map "@charset" chartreuse check if three code points would start an ident sequence check if three code points would start a number check if three code points would start a unicode-range check if two code points are a valid escape check the completion record child child combinator child css rules child selector chinese chocolate chromatic adaptation transform chromaticity circled-lower-latin clamp a grid area class selector clearance clearance. clear view transition clipping path clipping region close to the viewport clustered scripts collapse collapsed collapsed flex item collapsed grid track collapsed gutter collapsed margin collapse through collapsible white space collapsing margin collection of media queries <color> color color functions color scheme color scheme preference color scheme support color space color stop color stop list color transition hint column box column break column gap column height column rule column width combinator in css2 in selectors-4, for selector combinators in css2 in selectors-3 combined duration combining shadow lists comments commit computed styles compare media queries compatible baseline alignment preferences compatible units complete completed transition complex selector component keyword component value composite composited value composite face composite operation compositeoperation composite operation accumulate composite operation add composite operation replace composition compound selector compute a property value computed color computed flag computed <image> computed keyframe offset computed keyframe offsets computed keyframes computed repeat notation computed track list computed track size computed value computed values compute missing keyframe offsets concrete object size conditional group rule conditional import conditionally hang conformance conforming scripted web animations user agent consecutive constraint rectangle constructed flag constructor document consume a block consume a block's contents consume a component value consume a declaration consume a function consume a list of component values consume a list of declarations consume a list of rules consume an at-rule consume an escaped code point consume an ident-like token consume an ident sequence consume a number consume a numeric token consume a qualified rule consume a simple block consume a string token consume a style block's contents consume a stylesheet's contents consume a token in css-syntax-3 in css-syntax-3, for token stream in css-syntax-3, for tokenizer consume a unicode-range token consume a url token consume comments consume the next input token consume the remnants of a bad declaration consume the remnants of a bad url consume the value of a unicode-range descriptor contain constraint containing block containing block chain containing block for all descendants containing block::initial containment content content area content-based minimum size in css-flexbox-1 in css-grid-1 content box content distribution content-distribution content-distribution properties content edge content height content language content (of a box) content::of a box content rect content::rendered contents content size suggestion in css-flexbox-1 in css-grid-1 content width content writing system continuous media 'continuous' media group convert a color convert a string to a number coordinated self-alignment preference coral cornflowerblue cornsilk <counter> counter counter() counter properties counters counter scope counter style counter symbol cover constraint create a constructed cssstylesheet create a css style sheet create a medialist object create and populate a resizeobserverentry creator crimson cross axis cross-axis cross-axis baseline set cross dimension cross-end cross size cross size property cross-start css bracketed range notation css color profile css-connected css counters set css declaration css declaration block css feature queries cssfontfacerule cssfontfeaturevaluesrule css gamut mapped css gamut mapping algorithms css ident css identifier css ident sequence css property to idl attribute css qualified name css rule css rules css style sheet css style sheet set css style sheet set name css value definition syntax css-wide keywords cubic bézier easing function current currentcolor current finished promise current input code point current input token current iteration current iteration index currently relevant to the user current ready promise current time in web-animations-1, for animation in web-animations-1, for timeline current transformation matrix current value cursive cursive script custom property cyan cyclic percentage size cylindrical polar color d50 d65 darkblue dark color scheme darkcyan darkgoldenrod darkgray darkgreen darkgrey darkkhaki darkmagenta darkolivegreen darkorange darkorchid darkred darksalmon darkseagreen darkslateblue darkslategray darkslategrey darkturquoise darkviolet declaration in css-syntax-3, for CSS in css2 declaration block declarations declared declared value decode bytes decorating box decreasing deeppink deepskyblue default default document timeline default face default namespace default object size default sizing algorithm default style sheet definite in css-flexbox-1 in css-sizing-3 definite column position definite column span definite grid position definite grid span definite position definite row position definite row span definite size in css-flexbox-1 in css-sizing-3 definite span deliver resize loop error notification descendant descendant combinator descendant-selectors descriptor descriptor declarations destination determine the device pixel ratio determine the fallback encoding determine the scroll-into-view position determine the used color scheme device pixel dice digit dimension dimgray dimgrey directed progress direction-agnostic size directional embedding directional keyword directional override disabled flag disallow modification flag discard a mark discard a token discard whitespace discrete display type distributed alignment distribute extra space document in css-speech-1 in css-style-attr in cssom-view-1, for MediaQueryList document for timing document language document order document or shadow root css style sheets document-scoped view transition name document timeline document time space document tree document white space document white space characters dodgerblue dominant baseline dynamic view transition style sheet easing function east asian width property edge effect easing function effective character map effective percentage effective playback rate effect stack effect target effect value element in css-display-3, for CSS in css2 element color scheme element contents element::following element::preceding element tree emoji presentation participating code points empty in css-syntax-3, for token stream in css2 emulated forced colors theme data em (unit) enable a css style sheet set enabled css style sheet set encapsulation contexts end end delay ending edges ending point ending shape ending token endmost endpoint-inclusive active interval end time in css-transitions-1, for transition in web-animations-1 in web-animations-1, for animation effect end value environment encoding eof code point equivalent colors equivalent path in motion-1, for <basic-shape> in motion-1, for inset() in motion-1, for rect() in motion-1, for xywh() escape a character escape a character as code point escaped as code point escaping establish an independent formatting context establish an orthogonal flow established an independent formatting context establishes an independent formatting context establishing an independent formatting context evaluate media queries and report changes evaluating a selector exact matching excluded subtree expanded name explicit grid explicit grid column explicit grid properties explicit grid row explicit grid track explicitly-assigned line name extrinsic sizing ex (unit) fallback fallback alignment fallback size false in the negative range fantasy far away from the viewport featureless feature value block fetch a css style sheet fetch a font fetch an external color profile fetch an @import fictional tag sequence fill mode filter code points filtered code points filter function filter primitive filter primitive attributes filter primitive subregion filter primitive tree filter region final css style sheets find the matching font faces finish an animation finished finished promise finish event finish notification steps fire a font load event firebrick :first first available font first-baseline alignment first-baseline content-alignment first baselines first-baseline self-alignment first baseline set :first-child first-child first cross-axis baseline set first formatted line :first-letter first-letter :first-line first-line first main-axis baseline set first symbol value fit-content block size fit-content inline size fit-content size fixed position fixed-positioned fixed-positioned box fixed positioning containing block fixed sizing function flex base size flex basis flex container flex direction flex factor in css-flexbox-1 in css-grid-1, for grid-template-columns, grid-template-rows flex factor sum flex formatting context flex fraction flex grow factor flexible flexible length flexible sizing function flexible tracks flex item flex layout flex-level flex line flex shrink factor float area float rules floralwhite flow layout flow of an element flow-relative flow-relative direction flush the update callback queue :focus focus focus (pseudo-class) following element font block period font download timer font failure period font feature value block font feature value declaration font-relative lengths font source font specific font swap period footnote forced break forced break values forced colors mode forced colors mode emulation color palettes forced line break forced paragraph break forestgreen formatting context formatting structure forward-compatible parsing forwards fragment fragmentainer fragmentation fragmentation break fragmentation container fragmentation context fragmentation direction fragmentation root fragmented flow free space <frequency> fuchsia full-size full-size kana full-width fully clipped fully inflexible fully visible function functional notation functional pseudo-class functional pseudo-element gainsboro gamut gamut-map gather active observations at depth gather active resize observations gather active resize observations at depth general category generate a counter generate a counter representation generate baselines generated content <generic-voice> get emulated forced colors theme data get the bounding box ghostwhite global animation list global view transition user agent style sheet go gold goldenrod gradient-average-color gradient box gradient center gradient function gradient line grapheme cluster gray graytext green greenyellow grey grid grid area grid cell grid column grid column line grid container grid formatting context grid item grid item placement algorithm grid layout grid layout algorithm grid-level grid line 'grid' media group grid-modified document order grid order grid placement grid-placement property grid position grid row grid row line grid sizing algorithm grid span grid track group animation name rule group keyframes group styles rule growth limit guaranteed-invalid value gutter half-width handle transition frame hang hanging glyph has active observations has active resize observations :has-allowed pseudo-element has skipped observations has skipped resize observations height in css-sizing-3 in css-writing-modes-4 in cssom-view-1, for supported open() feature name hex color hex color notation hex digit highlight highlighttext hold time honeydew horizontal axis horizontal-axis horizontal block flow horizontal dimension horizontal offset horizontal-only horizontal script horizontal typographic mode horizontal writing mode host language host syntax hotpink :hover hover (pseudo-class) html-compatible serialization is requested http-default-style hyphenate hyphenation hyphenation opportunity hyphen-separated matching hypothetical cross size hypothetical fr size hypothetical main size ident ident code point identifier in css-values-3, for CSS in css2 identity transform identity transform function ident sequence ident-start code point idl attribute name to animation property name idl attribute to css property idle idle phase id selector ignore ignored ignore unknown ignore valid illegal image animation name rule image pair isolation rule implicit grid implicit grid column implicit grid lines implicit grid properties implicit grid row implicit grid track implicitly-assigned line name implicitly-named area @import important important flag import conditions inactiveborder inactivecaption inactivecaptiontext inactive timeline increasing indefinite in css-flexbox-1 in css-sizing-3 indefinite size in css-flexbox-1 in css-sizing-3 independent formatting context index indianred indicate focus indigo in effect infinitely growable in flow in-flow in-flow box infobackground infotext in-gamut inherit in css-cascade-5 in css-cascade-5, for CSS inheritance in css-cascade-5 in css-cascade-5, for CSS inherit counters inherited property inherited value initial containing block initial fixed containing block initial free space initial representation for the counter value initial snapshot containing block size initial value inline inline axis inline-axis inline base direction inline block inline-block inline block box inline box inline dimension inline end inline-end inline formatting context inline-level inline-level box inline-level boxes inline-level content inline-level element inline-level elements inline size inline-size inline-size containment inline start inline-start inlinification inlinify inner block size inner box-shadow inner display type inner edge inner height inner inline size innermost inner size inner width in play input progress value input stream input value pseudo-classes insert a css rule inset-modified containing block inset properties installed font fallback instantiate counter instant scroll integer intended direction intended direction and end position intended end position 'interactive media group internal ruby box internal ruby element internal table box internal table element interpolation color space interpreter in css-namespaces-3 in css-style-attr intrinsic dimensions intrinsic size intrinsic size constraint intrinsic size contribution intrinsic sizing intrinsic sizing function invalid invalid at computed-value time invalid color invalid image invalid rule error invalid selector invisible box isolated sequence isolation iteration count iteration duration iteration index iteration interval iteration order iteration progress iteration start iteration time iteration time space ivory japanese justification opportunity keyframe keyframe effect keyframe offset keyframe-specific composite operation keyframe-specific easing function keyword khaki known korean :lang lang (pseudo-class) language range last-baseline alignment last-baseline content-alignment last baselines last-baseline self-alignment last baseline set last cross-axis baseline set last css style sheet set name last main-axis baseline set lavender lavenderblush lawngreen layer name laying out in-place layout containment layout containment box layout-internal layout viewport :left left in css-writing-modes-4 in cssom-view-1, for supported open() feature name leftover space legacy color syntax legacy name alias legacy selector alias legacy shorthand legacy value alias lemonchiffon letter in css-syntax-3 in css-text-3 lightblue light color scheme lightcoral lightcyan lightgoldenrodyellow lightgray lightgreen lightgrey lightpink lightsalmon lightseagreen lightskyblue lightslategray lightslategrey light source lightsteelblue lightyellow lime limegreen limited max-content contribution limited min-content contribution linear easing function linear timing function line box line break in css-break-3 in css-text-3 line breaking line breaking process line-left linen line name line name set line orientation line-over line-relative line-relative direction line-right line-under :link link (pseudo-class) list item list-item list of complex selectors list of compound selectors list of selectors list of simple selectors list properties loading image local coordinate system local time local time space local url flag location logical combination pseudo-classes logical height logical property group logical width longer longhand longhand property loosely sorted by offset lowercase letter luminance magenta main axis main-axis main-axis baseline set main dimension main-end main size main size property main-start map document language elements to table elements mapping logic margin margin area margin box margin edge margin (of a box) margin::of a box margin properties <margin-width> mark marked indexes marker marker box marker image marker string maroon mask border image mask border image area mask image mask layer image mask painting area mask-position mask positioning area mask-size match match a complex selector against an element match a selector against an element match a selector against a pseudo-element match a selector against a tree matches state matching transition delay matching transition duration matching transition-property value matching transition timing function max-content max-content block size max-content block-size contribution max-content constraint max-content contribution max-content inline size max-content inline-size contribution max-content size max cross size max cross size property max height maximum allowed code point maximum height maximum size maximum width max inner height max inner width max main size max main size property max size max size property max track sizing function max width may media in css2 in cssom-1, for CSSStyleSheet in cssom-view-1, for MediaQueryList media condition media-dependent import media feature media group media groups media query media query list in cssom-view-1, for MediaQueryList in mediaqueries-4 media query modifier media type mediumaquamarine mediumblue mediumorchid mediumpurple mediumseagreen mediumslateblue mediumspringgreen mediumturquoise mediumvioletred menu menutext message entity midnightblue min-content min-content block size min-content block-size contribution min-content constraint min-content contribution min-content inline size min-content inline-size contribution min-content size min cross size min cross size property minde min height minimum contribution minimum height minimum size minimum width min inner height min inner width min main size min main size property min size min size property mintcream min track sizing function min width missing missing color component missing component mistyrose moccasin modern color syntax monolithic monospace monotonically increasing timeline multicol container multi-col line multicol line multi-column container multi-column formatting context multi-column layout multi-column line multi-column spanner multi-column spanning element multi-line flex container multiple declarations multiply must must not naively converted to cmyk naively converted to rgba naively convert from cmyk to rgba naively convert from rgba to cmyk name named cell token named color named elements named grid area named view transition pseudo-elements namespace prefix name-start code point natural aspect ratio natural dimension natural end-point natural height natural size natural width navajowhite navy nearest neighbor neutral value for composition new element newline next input code point next input token next-sibling combinator next token non-ascii code point non-ascii ident code point none 'none'::as display value non-overridable counter-style names non-printable code point non-replaced non-replaced element normal in css-cascade-5 in web-animations-1, for playback direction normalize into a token stream normalize non-finite values not animatable not determined null cell token number numeric data types objects object size negotiation occupied offset anchor point offset distance offsetk offset path offset position offset starting position offset transform old backdrop-filter old color-scheme old direction old height old image oldlace old mix-blend-mode old text-orientation old transform old width old writing-mode olive olivedrab opacity opaque black operating coordinate space optimal viewing region optional orange orangered orchid order-modified document order origin original containing block originally specified color space originating element originating pseudo-element origin-clean flag origin color origin time orthogonal orthogonal flow other space separators outer block size outer box-shadow outer display type outer edge outer height outer inline size outer size outer width outline out of flow out-of-flow out-of-flow box out of gamut output of the cascade output progress value outset-adjusted border radius over overall progress overflow overflow alignment overflow columns overflow directions override the color scheme overriding preference owner css rule owner node in cssom-1, for CSSStyleDeclaration in cssom-1, for CSSStyleSheet padding padding area padding box padding edge padding (of a box) padding::of a box padding properties <padding-width> @page page area page box page break page color scheme page context page-context paged media 'paged' media group page selector page's supported color scheme page's supported color schemes page zoom pagination paint containment paint containment box palegoldenrod palegreen paleturquoise palevioletred papayawhip parent parent box parent css rule in cssom-1, for CSSRule in cssom-1, for CSSStyleDeclaration parent css style sheet in cssom-1, for CSSRule in cssom-1, for CSSStyleSheet parse parse a block's contents parse a comma-separated list according to a css grammar parse a comma-separated list of component values parse a component value parse a css <color> value parse a css declaration block parse a css rule parse a css stylesheet parse a css value parse a declaration parse a group of selectors parse a list parse a list of component values parse a list of css page selectors parse a list of declarations parse a list of rules parse a media query parse a media query list parse a relative selector parse a rule parse as a forgiving selector list parse a selector parse a style block's contents parse a stylesheet parse a stylesheet's contents parse error parse something according to a css grammar parsing a list partially visible participates in baseline alignment pass through filter pause an animation paused peachpuff pending animation event queue pending on the environment pending pause task pending playback rate pending play task pending scrollend event targets pending scroll events pending scroll event targets pending-substitution value percentage perform a scroll in cssom-view-1 in cssom-view-1, for viewport perform pending transition operations persisted replace state persistent css style sheet perspective matrix peru phase physical physical bottom physical dimensions physical direction physical left physical right physical top physical unit pink pixel pixel unit play an animation playback control playback direction playback rate play state plum positional alignment position box positioned positioned box positioned element/box positioning scheme positioning schemes: post-multiplied post-multiply potentially scrollable powderblue powerless color component preceding element preferred aspect ratio preferred color scheme preferred css style sheet set name preferred height preferred order preferred size preferred size property preferred width pre-multiplied premultiplied pre-multiply prepare a color col1 for conversion preserved tokens preserved white space previous current time primary filter primitive tree principal block-level box principal box principal writing mode priority candidates process process a keyframe-like object process a keyframes argument prolog propagate propagation proper table child proper table row parent property in css-cascade-5, for CSS in css2 property declarations property name proximity to the viewport pseudo-class pseudo-classes pseudo-classes:::active pseudo-classes:::focus pseudo-classes:::hover pseudo-classes:::lang pseudo-classes:::link pseudo-classes:::visited pseudo-class:::first pseudo-class:::left pseudo-class:::right pseudo-compound selector pseudo-element root pseudo-elements pseudo-elements:::after in css2 in css2 pseudo-elements:::before in css2 in css2 pseudo-elements:::first-letter pseudo-elements:::first-line pseudo-element tree purple quad width qualified rule range context ray trace gamut map readonly flag ready ready promise recommended reconsume the current input code point reconsume the current input token rectangular orthogonal color red reference box in css-shapes-1, for <basic-shape> in css-transforms-1 reference pixel region break relative color relative color processing space relative length relative length unit relatively position relatively-positioned relatively positioned box relative position relative positioning relative scroll relative selector relative selector anchor elements relative units relevant relevant animations relevant animations for a subtree relevant to the user remaining fragmentainer extent remaining free space remove a css rule remove a css style sheet removed replace state remove event remove replaced animations rendered content rendering suppression for view transitions render with a fallback font face render with an invisible fallback font face repeatable list replaceable animation replaced replaced element replace state representation required required conversion reset an animation's pending tasks reset-only sub-property re-snap resolved type resolved value resolved value special case property resolved value special case property like color resolved value special case property like height resolved value special case property like top resolve to srgb restore a mark reverse reverse an animation reversed reversing-adjusted start value reversing shortening factor :right right root root element rosybrown row group box row groups royalblue rule rule set rules on anonymous table objects run-in run-in box run-in sequence running running transition run snapshot post-layout state steps run the resize steps run the scroll steps saddlebrown salmon sandybrown sans-serif scaled flex shrink factor scale factor scheduled event time schedule the update callback scope scoped scoped properties scoped property scoped selector scoped to an element scoped to an element's sub-tree scoped to a sub-tree scoped to the element scoped to the element's sub-tree scoped to the sub-tree scoping root screen reader script property scroll anchoring bounding rect scroll an element scroll a target into view scrollbar scroll completed scrolling area scrolling area origin scrolling box scroll snap scroll snap area scroll snap container scroll snapport scroll snap position scroll to the beginning of the document seagreen seamlessly update the playback rate seashell seek segment break select a css style sheet set selector selector list selector::match selector matches selector::subject of self-alignment self-alignment properties semitone separated borders model sequence of simple selectors serialize a comma-separated list serialize a css component value serialize a css declaration serialize a css declaration block serialize a css rule serialize a css value serialize a function serialize a group of selectors serialize a list of css page selectors serialize a local serialize a media feature value serialize a media query serialize a media query list serialize an <an+b> value serialize an <a-n-plus-b> value serialize an identifier serialize as a string serialize a selector serialize a simple selector serialize a string serialize a url serialize a whitespace-separated list serif set set a css declaration set emulated forced colors theme data set entries set the associated effect of an animation set the current time set the playback rate set the start time set the timeline of an animation set up browsing context features setup transition pseudo-elements setup view transition shall shall not shared alignment context sheet sheets shorter shorthand shorthand properties shorthand property should should not show view transition tree sibling sideways typesetting sienna silently set the current time silver simple block simple iteration progress simple selector single-line flex container size size containment size containment box sizing as if empty sizing function sizing property skip its contents skipped contents skipping its contents skips its contents skip the view transition skyblue slateblue slategray slategrey small small kana smooth scroll smooth scroll aborted smooth scroll completed snapshot containing block snapshot containing block origin snapshot containing block size snow soft wrap break soft wrap opportunity source source document spaces space-separated matching space to fill span count specificity <specific-voice> specified order specified size specified size suggestion in css-flexbox-1 in css-grid-1 specified value specified values 'speech' media group spread break spread distance springgreen srgb srgb-linear stacking context stack level start start delay starting point startmost starts with an ident sequence starts with a number starts with a valid escape start time in css-transitions-1, for transition in web-animations-1, for animation start value start with an ident sequence start with a number statement at-rule 'static' media group static position static-position containing block static-position rectangle in css-align-3 in css-position-3 stationary scroll steelblue step easing function step position steps sticky position sticky-positioned sticky-positioned box sticky view rectangle stop or comma stretched stretch fit stretch-fit block size stretch-fit inline size stretch-fit size strictness value <string> stringification behavior stroke bounding box stronger inset structural pseudo-classes stuck on the environment style attribute style change event style containment style definitions style rule style sheet in css-namespaces-3 in css-speech-1 in css2 stylesheet stylesheet base url subject subject of a selector subject (of selector) subject of the selector subjects subjects of the selector sub-property sub-pseudo-element subsequent-sibling combinator substitute a var() support in css-conditional-3, for CSS in css-fonts-4 support a css selector supported css property supported open() feature name supported styling language support legacy color syntax supports queries suppression trigger suppression window svg layout box svg viewport origin box switch the fontfaceset to loaded switch the fontfaceset to loading synchronously replace the rules of a cssstylesheet synthesize baseline synthesized baseline system color pairings system colors system fonts table table caption box table element table grid box tables table wrapper box tabs tab size tab stop tabular container 'tactile' media group tagged image tan target element target main size target property target pseudo-selector teal text text/css text node text sequence textual data types thistle threeddarkshadow threedface threedhighlight threedlightshadow threedshadow thumb <time> timeline timeline associated with a document timeline time to origin-relative time time spaces time value timing function timing model timing nodes title tokenization tokenize tokenizer tokens token stream tomato top in css-writing-modes-4 in cssom-view-1, for supported open() feature name total length track tracking track list track section track sizing algorithm track sizing function transfer function element transfer function element attributes transferred size suggestion in css-flexbox-1 in css-grid-1 transformable element transformation matrix transformed element transformed progress transforms transitionable transition origin transition root pseudo-element transitions transparent transparent black trash token triangle trinary turquoise type in cssom-1, for CSSRule in cssom-1, for CSSStyleSheet type selector typeset sideways typesetting sideways typesetting upright typeset upright typographic character typographic character unit typographic letter unit typographic mode ua in css-speech-1 in css2 ua origin ua-origin ua style sheet ultimate originating element under underlying value unforced break unicode category unicode east asian width unicode general category unicode script unicode vertical orientation universal selector unknown unknown -webkit- pseudo-elements unoccupied unresolved unset untagged image untagged video update an animation's finished state update animations and send events update callback update callback done promise update callback queue update content relevancy for a document update currently relevant to the user update pseudo-element styles update style attribute for update the timing properties of an animation effect updating flag upper-alpha-legal uppercase letter upright typesetting url use a negative sign used color used color scheme used offset distance used value used values user user action pseudo-class user agent in css-speech-1 in css2 user-agent origin user-agent style sheet user agent (ua) user coordinate system user origin user-origin user style sheet uses a negative sign valid color valid image validity valid style sheet value in css-lists-3, for CSS counter in css2 in cssom-1, for CSS declaration value definition syntax values var() substitution vertical axis vertical-axis vertical block flow vertical dimension vertical offset vertical-only vertical orientation vertical script vertical typographic mode vertical writing mode viable candidate viewport viewport-percentage lengths view transition layer view transition name view transition page-visibility change steps view transition pseudo-elements view transitions view transition tree violet :visited visited (pseudo-class) visual angle unit visual formatting model 'visual' media group visual viewport volume weaker inset web animations animation model web animations api web animations model web animations timing model web-exposed available screen area web-exposed screen area wheat white white point whitesmoke white space in css-text-3 in selectors-4 whitespace white space characters width in css-sizing-3 in css-writing-modes-4 in cssom-view-1, for supported open() feature name window windowframe windowtext word separator word-separator character would start an ident sequence would start a number would start a unicode-range wrap in css-shapes-1 in css-text-3 wrapping in css-shapes-1 in css-text-3 writing mode x-axis x-height y-axis yellow yellowgreen 8.2. Selector Index * + > ~ :active ::after :after :any-link :autofill ::before :before :buffering :checked :default :defined :dir() :disabled :empty :enabled :first :first-child first-child ::first-letter :first-letter ::first-line :first-line :first-of-type :focus :focus-visible :focus-within :fullscreen :has() :hover :indeterminate :in-range :invalid :is() :lang in css2 in selectors-3 :lang() :last-child :last-of-type :left :link :matches() :modal :muted :not() :nth-child() :nth-last-child() :nth-last-of-type() :nth-of-type() :only-child :only-of-type :open :optional :out-of-range :paused :picture-in-picture :placeholder-shown :playing :popover-open :read-only :read-write :required :right :root :scope :seeking :stalled :target :unchecked :user-invalid :user-valid :valid ::view-transition ::view-transition-group() ::view-transition-image-pair() ::view-transition-new() ::view-transition-old() :visited :volume-locked :where() 8.3. At-Rule Index @annotation @character-variant @charset @color-profile @counter-style @font-face @font-feature-values @font-palette-values @historical-forms @import @keyframes @layer @media @namespace @ornaments @page @styleset @stylistic @supports @swash 8.4. Property Index --* align-content in css-align-3 in css-flexbox-1 align-items in css-align-3 in css-flexbox-1 align-self in css-align-3 in css-flexbox-1 all animation animation-delay animation-direction animation-duration animation-fill-mode animation-iteration-count animation-name animation-play-state animation-timing-function azimuth backface-visibility background background-attachment background-blend-mode background-clip background-color background-image background-origin background-position background-repeat background-size block-size border border-block border-block-color border-block-end border-block-end-color border-block-end-style border-block-end-width border-block-start border-block-start-color border-block-start-style border-block-start-width border-block-style border-block-width border-bottom border-bottom-color border-bottom-left-radius border-bottom-right-radius border-bottom-style border-bottom-width border-collapse border-color border-end-end-radius border-end-start-radius border-image border-image-outset border-image-repeat border-image-slice border-image-source border-image-width border-inline border-inline-color border-inline-end border-inline-end-color border-inline-end-style border-inline-end-width border-inline-start border-inline-start-color border-inline-start-style border-inline-start-width border-inline-style border-inline-width border-left border-left-color border-left-style border-left-width border-radius border-right border-right-color border-right-style border-right-width border-spacing border-start-end-radius border-start-start-radius border-style border-top border-top-color border-top-left-radius border-top-right-radius border-top-style border-top-width border-width bottom box-decoration-break box-shadow box-sizing in css-sizing-3 in css-ui-3 break-after break-before break-inside caption-side caret-color clear clip clip-path clip-rule color color-adjust color-interpolation-filters color-scheme column-count column-fill column-gap column-rule column-rule-color column-rule-style column-rule-width columns column-span column-width contain content content-visibility counter-increment counter-reset counter-set cue in css-speech-1 in css2 cue-after in css-speech-1 in css2 cue-before in css-speech-1 in css2 cursor direction display elevation empty-cells filter flex flex-basis flex-direction flex-flow flex-grow flex-shrink flex-wrap float flood-color flood-opacity font font-family font-feature-settings font-kerning font-language-override font-optical-sizing font-palette font-size font-size-adjust font-stretch font-style font-synthesis font-synthesis-position font-synthesis-small-caps font-synthesis-style font-synthesis-weight font-variant font-variant-alternates font-variant-caps font-variant-east-asian font-variant-emoji font-variant-ligatures font-variant-numeric font-variant-position font-variation-settings font-weight font-width forced-color-adjust gap glyph-orientation-vertical grid grid-area grid-auto-columns grid-auto-flow grid-auto-rows grid-column grid-column-end grid-column-gap grid-column-start grid-gap grid-row grid-row-end grid-row-gap grid-row-start grid-template grid-template-areas grid-template-columns grid-template-rows hanging-punctuation height hyphens image-orientation image-rendering inline-size inset inset-block inset-block-end inset-block-start inset-inline inset-inline-end inset-inline-start isolation justify-content in css-align-3 in css-flexbox-1 justify-items justify-self left letter-spacing lighting-color line-break line-height list-style list-style-image list-style-position list-style-type margin margin-block margin-block-end margin-block-start margin-bottom margin-inline margin-inline-end margin-inline-start margin-left margin-right margin-top marker-side mask mask-border mask-border-mode mask-border-outset mask-border-repeat mask-border-slice mask-border-source mask-border-width mask-clip mask-composite mask-image mask-mode mask-origin mask-position mask-repeat mask-size mask-type max-block-size max-height max-inline-size max-width min-block-size min-height min-inline-size min-width mix-blend-mode object-fit object-position offset offset-anchor offset-distance offset-path offset-position offset-rotate opacity order orphans outline outline-color outline-offset outline-style outline-width overflow overflow-anchor overflow-wrap padding padding-block padding-block-end padding-block-start padding-bottom padding-inline padding-inline-end padding-inline-start padding-left padding-right padding-top page-break-after page-break-before page-break-inside pause in css-speech-1 in css2 pause-after in css-speech-1 in css2 pause-before in css-speech-1 in css2 perspective perspective-origin pitch pitch-range place-content place-items place-self play-during position print-color-adjust property-name quotes resize rest rest-after rest-before richness right rotate row-gap scale scrollbar-color scrollbar-width scroll-margin scroll-margin-block scroll-margin-block-end scroll-margin-block-start scroll-margin-bottom scroll-margin-inline scroll-margin-inline-end scroll-margin-inline-start scroll-margin-left scroll-margin-right scroll-margin-top scroll-padding scroll-padding-block scroll-padding-block-end scroll-padding-block-start scroll-padding-bottom scroll-padding-inline scroll-padding-inline-end scroll-padding-inline-start scroll-padding-left scroll-padding-right scroll-padding-top scroll-snap-align scroll-snap-stop scroll-snap-type shape-image-threshold shape-margin shape-outside speak in css-speech-1 in css2 speak-as speak-header speak-numeral speak-punctuation speech-rate stress table-layout tab-size text-align text-align-all text-align-last text-combine-upright text-decoration text-decoration-color text-decoration-line text-decoration-style text-emphasis text-emphasis-color text-emphasis-position text-emphasis-style text-indent text-justify text-orientation text-overflow text-shadow text-transform text-underline-position top transform transform-box transform-origin transform-style transition transition-delay transition-duration transition-property transition-timing-function translate unicode-bidi vertical-align view-transition-name visibility voice-balance voice-duration voice-family in css-speech-1 in css2 voice-pitch voice-range voice-rate voice-stress voice-volume volume white-space widows width will-change word-break word-spacing word-wrap writing-mode z-index 8.5. Values Index a in css-color-5, for lab() in css-color-5, for oklab() a98-rgb absolute in css-position-3, for position in css-speech-1, for voice-pitch in css-speech-1, for voice-range absolute-colorimetric accentcolor accentcolortext activeborder activecaption activetext add additive alias aliceblue all in css-multicol-1, for column-span in css-transitions-1, for transition-property in css-writing-modes-4, for text-combine-upright in css2, for @media in mediaqueries-4, for @media allow-end all-petite-caps all-scroll all-small-caps alpha in css-color-5, for alpha() in css-color-5, for color() in css-color-5, for hsl() in css-color-5, for hwb() in css-color-5, for lab() in css-color-5, for lch() in css-color-5, for oklab() in css-color-5, for oklch() in css-color-5, for rgb() in css-masking-1, for mask-border-mode in css-masking-1, for mask-mode in css-masking-1, for mask-type alphabetic alternate alternate-reverse always in css-scroll-snap-1, for scroll-snap-stop in css-speech-1, for speak in css2, for page-break-before, page-break-after, page-break-inside <angle> annotation(<font-feature-value-name>) antiquewhite anywhere in css-text-3, for line-break in css-text-3, for overflow-wrap appworkspace aqua in css-color-4, for <color>, <named-color> in css2, for <color> aquamarine arabic-indic arc armenian in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type at <position> attr(x) aural auto in css-align-3, for align-self in css-align-3, for justify-self in css-backgrounds-3, for background-size in css-backgrounds-3, for border-image-width in css-break-3, for break-before, break-after in css-break-3, for break-inside, page-break-inside in css-color-adjust-1, for forced-color-adjust in css-contain-2, for content-visibility in css-counter-styles-3, for @counter-style/range in css-counter-styles-3, for @counter-style/speak-as in css-flexbox-1, for align-items, align-self in css-flexbox-1, for flex-basis in css-fonts-4, for @font-face/font-display in css-fonts-4, for font-kerning in css-fonts-4, for font-optical-sizing in css-fonts-4, for font-synthesis-position in css-fonts-4, for font-synthesis-small-caps in css-fonts-4, for font-synthesis-style in css-fonts-4, for font-synthesis-weight in css-grid-1, for <grid-line> in css-grid-1, for grid-template-columns, grid-template-rows in css-images-3, for image-rendering in css-multicol-1, for column-count in css-multicol-1, for column-fill in css-multicol-1, for column-width in css-position-3, for top, right, bottom, left, inset-block-start, inset-inline-start, inset-block-end, inset-inline-end, inset-block, inset-inline, inset in css-scroll-anchoring-1, for overflow-anchor in css-scroll-snap-1, for scroll-padding, scroll-padding-inline, scroll-padding-inline-start, scroll-padding-inline-end, scroll-padding-block, scroll-padding-block-start, scroll-padding-block-end in css-scrollbars-1, for scrollbar-color in css-scrollbars-1, for scrollbar-width in css-sizing-3, for width, height, min-width, min-height in css-speech-1, for speak in css-speech-1, for voice-duration in css-text-3, for hyphens in css-text-3, for line-break in css-text-3, for text-align-last in css-text-3, for text-justify in css-text-decor-3, for text-underline-position in css-ui-3, for caret-color in css-ui-3, for cursor in css-will-change-1, for will-change in css2, for <top>, <right>, <bottom>, <left> in css2, for clip in css2, for height in css2, for overflow in css2, for page-break-before, page-break-after, page-break-inside in css2, for table-layout in css2, for top, right, bottom, left in css2, for width in css2, for z-index in filter-effects-1, for color-interpolation-filters in motion-1, for offset-anchor in motion-1, for offset-position in motion-1, for offset-rotate auto-fill auto-fit [ auto-flow && dense? ] <'grid-auto-rows'>? / <'grid-template-columns'> avoid in css-break-3, for break-before, break-after in css-break-3, for break-inside, page-break-inside in css2, for page-break-before, page-break-after, page-break-inside avoid-column in css-break-3, for break-before, break-after in css-break-3, for break-inside, page-break-inside avoid-page in css-break-3, for break-before, break-after in css-break-3, for break-inside, page-break-inside avoid-region in css-break-3, for break-before, break-after in css-break-3, for break-inside, page-break-inside azure b in css-color-5, for color() in css-color-5, for hwb() in css-color-5, for lab() in css-color-5, for oklab() in css-color-5, for rgb() background backwards balance balance-all baseline in css-align-3, for justify-self, justify-items, align-content, align-self, align-items, <baseline-position> in css-flexbox-1, for align-items, align-self in css2, for vertical-align <basic-shape> beige bengali bidi-override bisque black in css-color-4, for <color>, <named-color> in css2, for <color> blanchedalmond blink in css-text-decor-3, for text-decoration-line in css2, for text-decoration block in css-display-3, for display, <display-outside> in css-fonts-4, for @font-face/font-display in css-scroll-snap-1, for scroll-snap-type in css2, for display blue in css-color-4, for <color>, <named-color> in css2, for <color> blueviolet bold bolder border-box in css-backgrounds-3, for background-clip in css-backgrounds-3, for background-origin in css-box-3, for <box>, <visual-box>, <layout-box>, <shape-box>, <geometry-box>, <paint-box>, <coord-box> in css-masking-1, for mask-clip in css-masking-1, for mask-origin in css-shapes-1, for <shape-box>, shape-outside in css-sizing-3, for box-sizing in css-transforms-1, for transform-box in css-ui-3, for box-sizing both in css-animations-1, for animation-fill-mode in css-scroll-snap-1, for scroll-snap-type in css2, for clear bottom in css-backgrounds-3, for background-position in css-transforms-1, for transform-origin in css-transforms-2, for perspective-origin in css2, for caption-side in css2, for vertical-align braille in css2, for @media in mediaqueries-4, for @media break-all break-spaces break-word in css-text-3, for overflow-wrap in css-text-3, for word-break brown bullets burlywood buttonborder buttonface buttonhighlight buttonshadow buttontext by c in css-color-5, for lch() in css-color-5, for oklch() cadetblue cambodian canvas canvastext capitalize caption captiontext ccw cell center in css-align-3, for <self-position>, <content-position>, justify-self, align-self, justify-content, align-content in css-backgrounds-3, for background-position in css-flexbox-1, for align-content in css-flexbox-1, for align-items, align-self in css-flexbox-1, for justify-content in css-scroll-snap-1, for scroll-snap-align in css-speech-1, for voice-balance in css-text-3, for text-align in css-transforms-1, for transform-origin in css-transforms-2, for perspective-origin ch character-variant(<font-feature-value-name>#) chartreuse child chocolate ch unit circle in css-counter-styles-3, for <counter-style-name> in css-images-3, for <radial-shape> in css-text-decor-3, for text-emphasis-style in css2 in css2, for list-style-type cjk-decimal cjk-earthly-branch cjk-heavenly-stem cjk-ideographic clip clone close close-quote in css2 in css2, for content closest-corner in css-images-3, for <radial-extent>, radial-gradient(), repeating-radial-gradient() in motion-1, for <ray-size> closest-side in css-images-3, for <radial-extent>, radial-gradient(), repeating-radial-gradient() in motion-1, for <ray-size> cm coarse collapse in css-display-3, for visibility in css2, for border-collapse <color> color color-burn color-cbdt color-colrv0 color-colrv1 color-dodge color-sbix color-svg col-resize column in css-break-3, for break-before, break-after in css-flexbox-1, for flex-direction in css-grid-1, for grid-auto-flow column-reverse common-ligatures condensed contain in css-backgrounds-3, for background-size in css-images-3, for object-fit in motion-1, for ray() content in css-contain-2, for contain in css-flexbox-1, for flex-basis content-box in css-backgrounds-3, for background-clip in css-backgrounds-3, for background-origin in css-box-3, for <box>, <visual-box>, <layout-box>, <shape-box>, <geometry-box>, <paint-box>, <coord-box> in css-masking-1, for mask-clip in css-masking-1, for mask-origin in css-shapes-1, for <shape-box>, shape-outside in css-sizing-3, for box-sizing in css-transforms-1, for transform-box in css-ui-3, for box-sizing contents in css-display-3, for display, <display-box> in css-will-change-1, for will-change context-menu contextual copy coral cornflowerblue cornsilk <counter> <counter-name> <integer>? in css-lists-3, for counter-reset in css-lists-3, for counter-set counter-increment in css-lists-3, for counter-set, counter-increment <counter-style-name> cover in css-backgrounds-3, for background-size in css-images-3, for object-fit crimson crisp-edges crosshair currentcolor cursive in css-fonts-4, for font-family, <generic-font-family> in css2, for <generic-family> <cursor-predefined> curve cw cyan cyclic dark in css-color-adjust-1, for color-scheme in css-fonts-4, for base-palette in css-fonts-4, for font-palette darkblue darkcyan darken darkgoldenrod darkgray darkgreen darkgrey darkkhaki darkmagenta darkolivegreen darkorange darkorchid darkred darksalmon darkseagreen darkslateblue darkslategray darkslategrey darkturquoise darkviolet dashed in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css2 in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style <decibel> decimal in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type decimal-leading-zero in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type deeppink deepskyblue default deg dense devanagari diagonal-fractions difference digits digits <integer>? digits <integer [2,4]>? dimgray dimgrey disc in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type disclosure-closed disclosure-open discretionary-ligatures display-p3 display-p3-linear distribute dodgerblue dot dotted in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css2 in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style double in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css2 in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style double-circle dpcm dpi dppx each-line ease ease-in ease-in-out ease-out economy ellipse ellipsis em embed embossed in css2, for @media in mediaqueries-4, for @media emoji em unit end in css-align-3, for <self-position>, <content-position>, justify-self, align-self, justify-content, align-content in css-easing-1, for steps() in css-scroll-snap-1, for scroll-snap-align in css-text-3, for text-align e-resize ethiopic-numeric evenodd ew-resize ex exact exclude exclusion expanded extends extra-condensed extra-expanded ex unit fallback fantasy in css-fonts-4, for font-family, <generic-font-family> in css2, for <generic-family> farthest-corner in css-images-3, for <radial-extent>, radial-gradient(), repeating-radial-gradient() in motion-1, for <ray-size> farthest-side in css-images-3, for <radial-extent>, radial-gradient(), repeating-radial-gradient() in motion-1, for <ray-size> fast in css-speech-1, for voice-rate in mediaqueries-4, for @media/update features-aat features-graphite features-opentype female field fieldtext fill in css-backgrounds-3, for border-image-slice in css-images-3, for object-fit in css-masking-1, for mask-border-slice fill-box in css-box-3, for <box>, <geometry-box>, <paint-box>, <coord-box> in css-masking-1, for clip-path in css-masking-1, for mask-clip in css-masking-1, for mask-origin in css-transforms-1, for transform-box filled fine firebrick first in css-align-3, for justify-self, justify-items, align-content, align-self, align-items, <baseline-position> in css-text-3, for hanging-punctuation first baseline fit-content(<length-percentage>) in css-sizing-3, for column-width in css-sizing-3, for width, min-width, max-width, height, min-height, max-height fixed in css-backgrounds-3, for background-attachment in css-counter-styles-3, for @counter-style/system in css-position-3, for position in css2, for table-layout flex in css-display-3, for display, <display-inside> in css-flexbox-1, for display <flex [0,∞]> <'flex-basis'> flex-end in css-align-3, for <self-position>, <content-position>, justify-self, align-self, justify-content, align-content in css-flexbox-1, for align-content in css-flexbox-1, for align-items, align-self in css-flexbox-1, for justify-content <'flex-grow'> <'flex-shrink'> flex-start in css-align-3, for <self-position>, <content-position>, justify-self, align-self, justify-content, align-content in css-flexbox-1, for align-content in css-flexbox-1, for align-items, align-self in css-flexbox-1, for justify-content flip floralwhite flow flow-root force-end forestgreen format( <font-format> ) forwards fr from-image fr unit fuchsia in css-color-4, for <color>, <named-color> in css2, for <color> full-size-kana full-width in css-fonts-4, for font-variant-east-asian in css-text-3, for text-transform g in css-color-5, for color() in css-color-5, for rgb() gainsboro generic(fangsong) generic(kai) generic(khmer-mul) generic(nastaliq) georgian in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type ghostwhite gold goldenrod grab grabbing grad gray in css-color-4, for <color>, <named-color> in css2, for <color> graytext green in css-color-4, for <color>, <named-color> in css2, for <color> greenyellow grey grid in css-display-3, for display, <display-inside> in css-grid-1, for display <'grid-template-rows'> / [ auto-flow && dense? ] <'grid-auto-columns'>? <'grid-template-rows'> / <'grid-template-columns'> groove in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css2 in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style gujarati gurmukhi h in css-color-5, for hsl() in css-color-5, for hwb() in css-color-5, for lch() in css-color-5, for oklch() half-border-box handheld in css2, for @media in mediaqueries-4, for @media hanging hard-light hebrew help hidden in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css-contain-2, for content-visibility in css-display-3, for visibility in css2 in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style in css2, for overflow hide high in css-speech-1, for voice-pitch in css-speech-1, for voice-range highlight highlighttext high-quality hiragana hiragana-iroha historical-forms historical-ligatures honeydew horizontal-tb hotpink hover hsl hue hwb hz icon in inactiveborder inactivecaption inactivecaptiontext incremental indianred indigo infinite in css-animations-1, for animation-iteration-count in mediaqueries-4, for @media/resolution infobackground infotext inherit initial inline in css-display-3, for display, <display-outside> in css-scroll-snap-1, for scroll-snap-type in css2, for display inline-block in css-display-3, for display, <display-legacy> in css2, for display inline-flex in css-display-3, for display, <display-legacy> in css-flexbox-1, for display inline-grid in css-display-3, for display, <display-legacy> in css-grid-1, for display inline-size inline-table in css-display-3, for display, <display-legacy> in css2 in css2, for display inset in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css-backgrounds-3, for box-shadow in css2 in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style inside [ <integer [-∞,-1]> | <integer [1,∞]> ] && <custom-ident>? inter-character interlace intersect inter-word invert in css-ui-3, for outline-color in css2 isolate isolate-override italic ivory japanese-formal in css-counter-styles-3, for <counter-style-name> in css-counter-styles-3, for <counter-style> japanese-informal in css-counter-styles-3, for <counter-style-name> in css-counter-styles-3, for <counter-style> jis04 jis78 jis83 jis90 jump-both jump-end jump-none jump-start justify justify-all kannada katakana katakana-iroha keep-all <keyframes-name> khaki khmer khz korean-hangul-formal korean-hanja-formal korean-hanja-informal l in css-color-5, for hsl() in css-color-5, for lab() in css-color-5, for lch() in css-color-5, for oklab() in css-color-5, for oklch() lab landscape lao large in css-shapes-1, for shape(), arc in css2, for font-size last in css-align-3, for justify-self, justify-items, align-content, align-self, align-items, <baseline-position> in css-text-3, for hanging-punctuation last baseline lavender lavenderblush lawngreen layout lch left in css-align-3, for justify-content, justify-self, justify-items in css-backgrounds-3, for background-position in css-break-3, for break-before, break-after in css-fonts-4, for font-style in css-speech-1, for voice-balance in css-text-3, for text-align in css-text-decor-3, for text-emphasis-position in css-text-decor-3, for text-underline-position in css-transforms-1, for transform-origin in css-transforms-2, for perspective-origin in css2, for clear in css2, for float in css2, for page-break-before, page-break-after, page-break-inside leftwards legacy lemonchiffon <length> in css-position-3, for top, right, bottom, left, inset-block-start, inset-inline-start, inset-block-end, inset-inline-end, inset-block, inset-inline, inset in css-text-3, for letter-spacing in css-text-3, for text-indent in css-text-3, for word-spacing in css2, for <border-width>, border-top-width, border-right-width, border-bottom-width, border-left-width, border-width in css2, for <padding-width> in css2, for top, right, bottom, left in css2, for vertical-align <length [0,∞]> <length-percentage [0,∞]>{2} light in css-color-adjust-1, for color-scheme in css-fonts-4, for base-palette in css-fonts-4, for font-palette lightblue lightcoral lightcyan lighten lighter lightgoldenrodyellow lightgray lightgreen lightgrey lightpink lightsalmon lightseagreen lightskyblue lightslategray lightslategrey lightsteelblue lightyellow lime in css-color-4, for <color>, <named-color> in css2, for <color> limegreen line linear linearrgb linen [ <line-names>? <string> <track-size>? <line-names>? ]+ [ / <explicit-track-list> ]? line-through in css-text-decor-3, for text-decoration-line in css2, for text-decoration lining-nums linktext list-item in css-display-3, for display, <display-listitem> in css-lists-3, for counter-increment, counter-set, counter-reset, counter(), counters() in css2, for display literal-punctuation local local( <font-family-name> ) logical loose loud low in css-speech-1, for voice-pitch in css-speech-1, for voice-range lower-alpha in css-counter-styles-3, for <counter-style-name> in css2, for list-style-type lower-armenian lowercase lower-greek in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type lower-latin in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type lower-roman in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type ltr luminance in css-masking-1, for mask-border-mode in css-masking-1, for mask-mode in css-masking-1, for mask-type luminosity magenta malayalam male mandatory manual margin-box in css-box-3, for <box>, <layout-box>, <shape-box>, <geometry-box> in css-shapes-1, for <shape-box>, shape-outside mark marktext maroon in css-color-4, for <color>, <named-color> in css2, for <color> match-parent in css-lists-3, for marker-side in css-text-3, for text-align match-self match-source math in css-fonts-4, for font-family in css-fonts-4, for font-size max-content in css-grid-1, for grid-template-columns, grid-template-rows in css-sizing-3, for column-width in css-sizing-3, for width, min-width, max-width, height, min-height, max-height medium in css-backgrounds-3, for <line-width>, border-width, border-top-width, border-left-width, border-bottom-width, border-right-width, border in css-speech-1, for pause-before, pause-after in css-speech-1, for rest-before, rest-after in css-speech-1, for voice-pitch in css-speech-1, for voice-range in css-speech-1, for voice-rate in css-speech-1, for voice-volume in css2, for <border-width>, border-top-width, border-right-width, border-bottom-width, border-left-width, border-width in css2, for font-size mediumaquamarine mediumblue mediumorchid mediumpurple mediumseagreen mediumslateblue mediumspringgreen mediumturquoise mediumvioletred menu in css-color-4, for <color>, <deprecated-color> in css-fonts-4, for font menutext message-box middle midnightblue min-content in css-grid-1, for grid-template-columns, grid-template-rows in css-sizing-3, for column-width in css-sizing-3, for width, min-width, max-width, height, min-height, max-height mintcream mistyrose mixed mm moccasin moderate mongolian monospace in css-fonts-4, for font-family, <generic-font-family> in css2, for <generic-family> move in css-shapes-1, for shape() in css-ui-3, for cursor ms multiply myanmar navajowhite navy in css-color-4, for <color>, <named-color> in css2, for <color> ne-resize nesw-resize neutral never no-clip no-close-quote in css2 in css2, for content no-common-ligatures no-contextual no-discretionary-ligatures no-drop no-historical-ligatures none in css-animations-1, for animation-fill-mode in css-animations-1, for animation-name in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css-backgrounds-3, for background-image in css-backgrounds-3, for box-shadow in css-color-4, for <color> in css-color-5, for light-dark() in css-color-adjust-1, for forced-color-adjust in css-contain-2, for contain in css-display-3, for display, <display-box> in css-flexbox-1, for flex in css-fonts-4, for font-kerning in css-fonts-4, for font-optical-sizing in css-fonts-4, for font-size-adjust in css-fonts-4, for font-synthesis-position in css-fonts-4, for font-synthesis-small-caps in css-fonts-4, for font-synthesis-style in css-fonts-4, for font-synthesis-weight in css-fonts-4, for font-variant in css-fonts-4, for font-variant-ligatures in css-grid-1, for grid-template in css-grid-1, for grid-template-areas in css-grid-1, for grid-template-rows, grid-template-columns in css-images-3, for image-orientation in css-images-3, for object-fit in css-lists-3, for counter-reset in css-lists-3, for counter-set counter-increment in css-lists-3, for counter-set, counter-increment in css-lists-3, for list-style-image in css-lists-3, for list-style-type in css-multicol-1, for column-span in css-scroll-anchoring-1, for overflow-anchor in css-scroll-snap-1, for scroll-snap-align in css-scroll-snap-1, for scroll-snap-type in css-scrollbars-1, for scrollbar-width in css-shapes-1, for shape-outside in css-sizing-3, for max-width, max-height in css-speech-1, for pause-before, pause-after in css-speech-1, for rest-before, rest-after in css-speech-1, for voice-stress in css-text-3, for hanging-punctuation in css-text-3, for hyphens in css-text-3, for text-justify in css-text-3, for text-transform in css-text-decor-3, for text-decoration-line in css-text-decor-3, for text-emphasis-style in css-transforms-2, for perspective in css-transforms-2, for perspective() in css-transforms-2, for translate, rotate, scale in css-transitions-1, for transition-property in css-ui-3, for cursor in css-view-transitions-1, for view-transition-name in css-writing-modes-4, for text-combine-upright in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style in css2, for clear in css2, for content in css2, for counter-reset, counter-increment in css2, for display in css2, for float in css2, for max-height in css2, for max-width in css2, for quotes in css2, for text-decoration in mediaqueries-4, for @media/hover in mediaqueries-4, for @media/overflow-block in mediaqueries-4, for @media/overflow-inline in mediaqueries-4, for @media/pointer in mediaqueries-4, for @media/update in motion-1, for offset-path 'none'::as border style nonzero no-open-quote in css2 in css2, for content no-punctuation no-repeat normal in compositing-1, for <blend-mode> in css-align-3, for align-self in css-align-3, for justify-content, align-content in css-align-3, for justify-self in css-align-3, for row-gap, column-gap, gap in css-animations-1, for animation-direction in css-color-adjust-1, for color-scheme in css-fonts-4, for font-feature-settings in css-fonts-4, for font-kerning in css-fonts-4, for font-language override in css-fonts-4, for font-palette in css-fonts-4, for font-style in css-fonts-4, for font-variant in css-fonts-4, for font-variant-alternates in css-fonts-4, for font-variant-caps in css-fonts-4, for font-variant-east-asian in css-fonts-4, for font-variant-emoji in css-fonts-4, for font-variant-ligatures in css-fonts-4, for font-variant-numeric in css-fonts-4, for font-variant-position in css-fonts-4, for font-weight in css-fonts-4, for font-width in css-scroll-snap-1, for scroll-snap-stop in css-speech-1, for speak-as in css-speech-1, for voice-rate in css-speech-1, for voice-stress in css-text-3, for letter-spacing in css-text-3, for line-break in css-text-3, for overflow-wrap in css-text-3, for white-space in css-text-3, for word-break in css-text-3, for word-spacing in css-writing-modes-4, for unicode-bidi in css2, for content in css2, for line-height in motion-1, for offset-position not not-allowed nowrap in css-flexbox-1, for flex-wrap in css-text-3, for white-space n-resize ns-resize numbers numeric nw-resize nwse-resize objectboundingbox in css-masking-1, for clipPathUnits in css-masking-1, for maskContentUnits in css-masking-1, for maskUnits oblique oblique <angle [-90deg,90deg]>? oblique-only off <offset-path> || <coord-box> oklab oklch old oldlace oldstyle-nums olive in css-color-4, for <color>, <named-color> in css2, for <color> olivedrab on only in css-color-adjust-1, for color-scheme in mediaqueries-4, for @media open open-quote in css2 in css2, for content optional orange in css-color-4, for <color>, <named-color> in css2, for <color> orangered orchid ordinal oriya ornaments(<font-feature-value-name>) outset in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css2 in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style outside over overlay overline in css-text-decor-3, for text-decoration-line in css2, for text-decoration p3 padding-box in css-backgrounds-3, for background-clip in css-backgrounds-3, for background-origin in css-box-3, for <box>, <visual-box>, <layout-box>, <shape-box>, <geometry-box>, <paint-box>, <coord-box> in css-masking-1, for mask-clip in css-masking-1, for mask-origin in css-shapes-1, for <shape-box>, shape-outside page paged paint palegoldenrod palegreen palettes paleturquoise palevioletred papayawhip paused pc peachpuff <percentage> in css-position-3, for top, right, bottom, left, inset-block-start, inset-inline-start, inset-block-end, inset-inline-end, inset-block, inset-inline, inset in css-text-3, for text-indent in css2, for <padding-width> in css2, for top, right, bottom, left in css2, for vertical-align perceptual persian peru petite-caps pink pixelated plaintext plum pointer portrait powderblue pre pre-line preserve preserve-parent-color pre-wrap print in css2, for @media in mediaqueries-4, for @media progress progressive projection in css2, for @media in mediaqueries-4, for @media prophoto-rgb proportional-nums proportional-width proximity pt purple in css-color-4, for <color>, <named-color> in css2, for <color> px q r in css-color-5, for color() in css-color-5, for rgb() rad <radial-shape> <radial-size> <ray()> <ray-size> rebeccapurple rec2020 in css-color-4, for color() in mediaqueries-4, for @media/color-gamut :recto recto in css-break-3, for break-before, break-after in css-logical-1, for logical-page red in css-color-4, for <color>, <named-color> in css2, for <color> reduced region relative relative-colorimetric rem rem unit repeat in css-backgrounds-3, for background-repeat in css-backgrounds-3, for border-image-repeat repeat-x repeat-y reverse in css-animations-1, for animation-direction in motion-1, for offset-rotate <reversed-counter-name> <integer>? revert revert-layer revert-rule ridge in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css2 in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style right in css-align-3, for justify-content, justify-self, justify-items in css-backgrounds-3, for background-position in css-break-3, for break-before, break-after in css-fonts-4, for font-style in css-speech-1, for voice-balance in css-text-3, for text-align in css-text-decor-3, for text-emphasis-position in css-text-decor-3, for text-underline-position in css-transforms-1, for transform-origin in css-transforms-2, for perspective-origin in css2, for clear in css2, for float in css2, for page-break-before, page-break-after, page-break-inside rightwards rosybrown round in css-backgrounds-3, for background-repeat in css-backgrounds-3, for border-image-repeat row in css-flexbox-1, for flex-direction in css-grid-1, for grid-auto-flow row-resize row-reverse royalblue rtl ruby in css-display-3, for display, <display-inside> in css-fonts-4, for font-variant-east-asian ruby-base ruby-base-container ruby-text ruby-text-container run-in running s in css-color-5, for hsl() in css-values-3, for <time> saddlebrown safe salmon sandybrown sans-serif in css-fonts-4, for font-family, <generic-font-family> in css2, for <generic-family> saturation in compositing-1, for <blend-mode> in css-color-5, for @color-profile/rendering-intent scale-down screen in compositing-1, for <blend-mode> in css2, for @media in mediaqueries-4, for @media scroll in css-backgrounds-3, for background-attachment in css2, for overflow in mediaqueries-4, for @media/overflow-block in mediaqueries-4, for @media/overflow-inline scrollbar scroll-position seagreen seashell selecteditem selecteditemtext self-end self-start semi-condensed semi-expanded <semitones> in css-speech-1, for voice-pitch in css-speech-1, for voice-range separate se-resize serif in css-fonts-4, for font-family, <generic-font-family> in css2, for <generic-family> sesame show sides sideways sideways-lr sideways-right sideways-rl sienna silent silver in css-color-4, for <color>, <named-color> in css2, for <color> simp-chinese-formal simp-chinese-informal simplified size skyblue slashed-zero slateblue slategray slategrey slice slow in css-speech-1, for voice-rate in mediaqueries-4, for @media/update small in css-shapes-1, for shape(), arc in css2, for font-size small-caps in css-fonts-4, for font-variant-caps in css2, for font-style small-caption smooth in css-images-3, for image-rendering in css-shapes-1, for shape() snow soft soft-light solid in css-backgrounds-3, for <line-style>, border-style, border-top-style, border-left-style, border-bottom-style, border-right-style, border in css2 in css2, for <border-style>, border-top-style, border-right-style, border-bottom-style, border-left-style, border-style space in css-backgrounds-3, for background-repeat in css-backgrounds-3, for border-image-repeat space-around in css-align-3, for align-content, justify-content, <content-distribution> in css-flexbox-1, for align-content in css-flexbox-1, for justify-content space-between in css-align-3, for align-content, justify-content, <content-distribution> in css-flexbox-1, for align-content in css-flexbox-1, for justify-content space-evenly span && [ <integer [1,∞]> || <custom-ident> ] speech in css2, for @media in mediaqueries-4, for @media spell-out in css-counter-styles-3, for @counter-style/speak-as in css-speech-1, for speak-as springgreen square in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type s-resize srgb in css-color-4, for color() in filter-effects-1, for color-interpolation-filters in mediaqueries-4, for @media/color-gamut srgb-linear stacked-fractions start in css-align-3, for <self-position>, <content-position>, justify-self, align-self, justify-content, align-content in css-easing-1, for steps() in css-scroll-snap-1, for scroll-snap-align in css-text-3, for text-align static status-bar steelblue step-end step-start sticky stretch in css-align-3, for align-content, justify-content, <content-distribution> in css-align-3, for align-self in css-align-3, for justify-self in css-backgrounds-3, for border-image-repeat in css-flexbox-1, for align-content in css-flexbox-1, for align-items, align-self strict in css-contain-2, for contain in css-text-3, for line-break <string> <string>+ [<string> <string>]+ stroke-box in css-box-3, for <box>, <geometry-box>, <paint-box>, <coord-box> in css-masking-1, for clip-path in css-masking-1, for mask-clip in css-masking-1, for mask-origin in css-transforms-1, for transform-box strong in css-speech-1, for pause-before, pause-after in css-speech-1, for rest-before, rest-after in css-speech-1, for voice-stress style styleset(<font-feature-value-name>#) stylistic(<font-feature-value-name>) sub in css-fonts-4, for font-variant-position in css2, for vertical-align subtract super in css-fonts-4, for font-variant-position in css2, for vertical-align swap swash(<font-feature-value-name>) sw-resize symbolic system-ui table in css-display-3, for display, <display-inside> in css2 in css2, for display table-caption in css-display-3, for display, <display-internal> in css2 in css2, for display table-cell in css-display-3, for display, <display-internal> in css2 in css2, for display table-column in css-display-3, for display, <display-internal> in css2 in css2, for display table-column-group in css-display-3, for display, <display-internal> in css2 in css2, for display table-footer-group in css-display-3, for display, <display-internal> in css2 in css2, for display table-header-group in css-display-3, for display, <display-internal> in css2 in css2, for display table-row in css-display-3, for display, <display-internal> in css2 in css2, for display table-row-group in css-display-3, for display, <display-internal> in css2 in css2, for display tabular-nums tamil tan teal in css-color-4, for <color>, <named-color> in css2, for <color> tech( <font-tech># ) telugu text in css-fonts-4, for font-variant-emoji in css-ui-3, for cursor text-bottom text-top thai thick in css-backgrounds-3, for <line-width>, border-width, border-top-width, border-left-width, border-bottom-width, border-right-width, border in css2, for <border-width>, border-top-width, border-right-width, border-bottom-width, border-left-width, border-width thin in css-backgrounds-3, for <line-width>, border-width, border-top-width, border-left-width, border-bottom-width, border-right-width, border in css-scrollbars-1, for scrollbar-width in css2, for <border-width>, border-top-width, border-right-width, border-bottom-width, border-left-width, border-width thistle threeddarkshadow threedface threedhighlight threedlightshadow threedshadow tibetan titling-caps to tomato top in css-backgrounds-3, for background-position in css-transforms-1, for transform-origin in css-transforms-2, for perspective-origin in css2, for caption-side in css2, for vertical-align <track-list> | <auto-track-list> trad-chinese-formal trad-chinese-informal traditional transparent in css-color-4, for <color> in css2, for border-color, border-top-color, border-right-color, border-bottom-color, border-left-color triangle tty in css2, for @media in mediaqueries-4, for @media turn turquoise tv in css2, for @media in mediaqueries-4, for @media ui-monospace ui-rounded ui-sans-serif ui-serif ultra-condensed ultra-expanded under in css-text-decor-3, for text-emphasis-position in css-text-decor-3, for text-underline-position underline in css-text-decor-3, for text-decoration-line in css2, for text-decoration unicase unicode unsafe unset upper-alpha in css-counter-styles-3, for <counter-style-name> in css2, for list-style-type upper-armenian uppercase upper-latin in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type upper-roman in css-counter-styles-3, for <counter-style-name> in css2 in css2, for list-style-type upright <uri> in css2, for background-image in css2, for content <url> userspaceonuse in css-masking-1, for clipPathUnits in css-masking-1, for maskContentUnits in css-masking-1, for maskUnits variations :verso verso in css-break-3, for break-before, break-after in css-logical-1, for logical-page vertical-lr vertical-rl vertical-text vh view-box in css-box-3, for <box>, <geometry-box>, <coord-box> in css-masking-1, for clip-path in css-masking-1, for mask-clip in css-masking-1, for mask-origin in css-transforms-1, for transform-box violet visible in css-contain-2, for content-visibility in css-display-3, for visibility in css2, for overflow visitedtext vmax vmin vw w wait weak in css-speech-1, for pause-before, pause-after in css-speech-1, for rest-before, rest-after wheat white in css-color-4, for <color>, <named-color> in css2, for <color> whitesmoke window windowframe windowtext words wrap wrap-reverse w-resize x in css-color-5, for color() in css-scroll-snap-1, for scroll-snap-type in css-transforms-2, for rotate x-fast x-high in css-speech-1, for voice-pitch in css-speech-1, for voice-range x-large x-loud x-low in css-speech-1, for voice-pitch in css-speech-1, for voice-range x-slow x-small x-soft x-strong in css-speech-1, for pause-before, pause-after in css-speech-1, for rest-before, rest-after x-weak in css-speech-1, for pause-before, pause-after in css-speech-1, for rest-before, rest-after xx-large xx-small xyz xyz-d50 xyz-d65 y in css-color-5, for color() in css-scroll-snap-1, for scroll-snap-type in css-transforms-2, for rotate yellow in css-color-4, for <color>, <named-color> in css2, for <color> yellowgreen young z in css-color-5, for color() in css-transforms-2, for rotate zoom-in zoom-out 9. Acknowledgements Special thanks to Florian Rivoal for creating the initial draft of the § 3.2.1 Experimentation and Unstable Features recommendations. Conformance Document conventions Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification. All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119] Examples in this specification are introduced with the words “for example” or are set apart from the normative text with class="example" , like this: This is an example of an informative example. Informative notes begin with the word “Note” and are set apart from the normative text with class="note" , like this: Note, this is an informative note. Advisements are normative sections styled to evoke special attention and are set apart from other normative text with <strong class="advisement"> , like this: UAs MUST provide an accessible alternative. Conformance classes Conformance to this specification is defined for three conformance classes: style sheet A CSS style sheet . renderer A UA that interprets the semantics of a style sheet and renders documents that use them. authoring tool A UA that writes a style sheet. A style sheet is conformant to this specification if all of its statements that use syntax defined in this module are valid according to the generic CSS grammar and the individual grammars of each feature defined in this module. A renderer is conformant to this specification if, in addition to interpreting the style sheet as defined by the appropriate specifications, it supports all the features defined by this specification by parsing them correctly and rendering the document accordingly. However, the inability of a UA to correctly render a document due to limitations of the device does not make the UA non-conformant. (For example, a UA is not required to render color on a monochrome monitor.) An authoring tool is conformant to this specification if it writes style sheets that are syntactically correct according to the generic CSS grammar and the individual grammars of each feature in this module, and meet all other conformance requirements of style sheets as described in this module. Partial implementations So that authors can exploit the forward-compatible parsing rules to assign fallback values, CSS renderers must treat as invalid (and ignore as appropriate ) any at-rules, properties, property values, keywords, and other syntactic constructs for which they have no usable level of support. In particular, user agents must not selectively ignore unsupported component values and honor supported values in a single multi-value property declaration: if any value is considered invalid (as unsupported values must be), CSS requires that the entire declaration be ignored. Implementations of Unstable and Proprietary Features To avoid clashes with future stable CSS features, the CSSWG recommends following best practices for the implementation of unstable features and proprietary extensions to CSS. Non-experimental implementations Once a specification reaches the Candidate Recommendation stage, non-experimental implementations are possible, and implementors should release an unprefixed implementation of any CR-level feature they can demonstrate to be correctly implemented according to spec. To establish and maintain the interoperability of CSS across implementations, the CSS Working Group requests that non-experimental CSS renderers submit an implementation report (and, if necessary, the testcases used for that implementation report) to the W3C before releasing an unprefixed implementation of any CSS features. Testcases submitted to W3C are subject to review and correction by the CSS Working Group. Further information on submitting testcases and implementation reports can be found from on the CSS Working Group’s website at https://www.w3.org/Style/CSS/Test/ . Questions should be directed to the [email protected] mailing list. References Normative References [COMPOSITING] Chris Harrelson. Compositing and Blending Level 1 . 21 March 2024. CRD. URL: https://www.w3.org/TR/compositing-1/ [CSS-BACKGROUNDS-3] Elika Etemad; Brad Kemper. CSS Backgrounds and Borders Module Level 3 . 11 March 2024. CRD. URL: https://www.w3.org/TR/css-backgrounds-3/ [CSS-BOX-3] Elika Etemad. CSS Box Model Module Level 3 . 11 April 2024. REC. URL: https://www.w3.org/TR/css-box-3/ [CSS-CASCADE-4] Elika Etemad; Tab Atkins Jr.. CSS Cascading and Inheritance Level 4 . 13 January 2022. CR. URL: https://www.w3.org/TR/css-cascade-4/ [CSS-COLOR-4] Tab Atkins Jr.; Chris Lilley; Lea Verou. CSS Color Module Level 4 . 2 May 2026. CRD. URL: https://www.w3.org/TR/css-color-4/ [CSS-COLOR-5] Chris Lilley; Una Kravets; Lea Verou. CSS Color Module Level 5 . 7 May 2026. WD. URL: https://www.w3.org/TR/css-color-5/ [CSS-CONDITIONAL-3] Chris Lilley; David Baron; Elika Etemad. CSS Conditional Rules Module Level 3 . 15 August 2024. CRD. URL: https://www.w3.org/TR/css-conditional-3/ [CSS-CONDITIONAL-5] Chris Lilley; et al. CSS Conditional Rules Module Level 5 . 30 October 2025. WD. URL: https://www.w3.org/TR/css-conditional-5/ [CSS-CONTAIN-1] Tab Atkins Jr.; Florian Rivoal. CSS Containment Module Level 1 . 25 June 2024. REC. URL: https://www.w3.org/TR/css-contain-1/ [CSS-CONTAIN-2] Tab Atkins Jr.; Florian Rivoal; Vladimir Levin. CSS Containment Module Level 2 . 17 September 2022. WD. URL: https://www.w3.org/TR/css-contain-2/ [CSS-COUNTER-STYLES-3] Tab Atkins Jr.. CSS Counter Styles Level 3 . 27 July 2021. CR. URL: https://www.w3.org/TR/css-counter-styles-3/ [CSS-DISPLAY-3] Elika Etemad; Tab Atkins Jr.. CSS Display Module Level 3 . 30 March 2023. CR. URL: https://www.w3.org/TR/css-display-3/ [CSS-EASING-1] Brian Birtles; Dean Jackson; Matt Rakow. CSS Easing Functions Level 1 . 13 February 2023. CRD. URL: https://www.w3.org/TR/css-easing-1/ [CSS-ENV-1] CSS Environment Variables Module Level 1 . 23 September 2025. FPWD. URL: https://www.w3.org/TR/css-env-1/ [CSS-FLEXBOX-1] Elika Etemad; Tab Atkins Jr.; Rossen Atanassov. CSS Flexible Box Layout Module Level 1 . 14 October 2025. CRD. URL: https://www.w3.org/TR/css-flexbox-1/ [CSS-FONTS-3] John Daggett; Myles Maxfield; Chris Lilley. CSS Fonts Module Level 3 . 20 September 2018. REC. URL: https://www.w3.org/TR/css-fonts-3/ [CSS-FONTS-4] Chris Lilley. CSS Fonts Module Level 4 . 22 April 2026. WD. URL: https://www.w3.org/TR/css-fonts-4/ [CSS-IMAGES-3] Tab Atkins Jr.; Elika Etemad; Lea Verou. CSS Images Module Level 3 . 18 December 2023. CRD. URL: https://www.w3.org/TR/css-images-3/ [CSS-IMAGES-4] Elika Etemad; Tab Atkins Jr.; Lea Verou. CSS Images Module Level 4 . 30 September 2025. WD. URL: https://www.w3.org/TR/css-images-4/ [CSS-INLINE-3] Elika Etemad. CSS Inline Layout Module Level 3 . 18 December 2024. WD. URL: https://www.w3.org/TR/css-inline-3/ [CSS-MULTICOL-1] Florian Rivoal; Rachel Andrew. CSS Multi-column Layout Module Level 1 . 16 May 2024. CR. URL: https://www.w3.org/TR/css-multicol-1/ [CSS-POSITION-3] Elika Etemad; Tab Atkins Jr.. CSS Positioned Layout Module Level 3 . 7 October 2025. WD. URL: https://www.w3.org/TR/css-position-3/ [CSS-PSEUDO-4] Elika Etemad; Alan Stearns. CSS Pseudo-Elements Module Level 4 . 27 June 2025. WD. URL: https://www.w3.org/TR/css-pseudo-4/ [CSS-SIZING-3] Tab Atkins Jr.; Elika Etemad. CSS Box Sizing Module Level 3 . 17 December 2021. WD. URL: https://www.w3.org/TR/css-sizing-3/ [CSS-SIZING-4] Tab Atkins Jr.; Elika Etemad; Jen Simmons. CSS Box Sizing Module Level 4 . 20 May 2021. WD. URL: https://www.w3.org/TR/css-sizing-4/ [CSS-STYLE-ATTR] Tantek Çelik; Elika Etemad. CSS Style Attributes . 7 November 2013. REC. URL: https://www.w3.org/TR/css-style-attr/ [CSS-SYNTAX-3] Tab Atkins Jr.; Simon Sapin. CSS Syntax Module Level 3 . 24 December 2021. CRD. URL: https://www.w3.org/TR/css-syntax-3/ [CSS-TEXT-4] Elika Etemad; et al. CSS Text Module Level 4 . 29 May 2024. WD. URL: https://www.w3.org/TR/css-text-4/ [CSS-TEXT-DECOR-4] Elika Etemad; Koji Ishii. CSS Text Decoration Module Level 4 . 4 May 2022. WD. URL: https://www.w3.org/TR/css-text-decor-4/ [CSS-TRANSFORMS-1] Simon Fraser; et al. CSS Transforms Module Level 1 . 14 February 2019. CR. URL: https://www.w3.org/TR/css-transforms-1/ [CSS-TRANSFORMS-2] Tab Atkins Jr.; et al. CSS Transforms Module Level 2 . 9 November 2021. WD. URL: https://www.w3.org/TR/css-transforms-2/ [CSS-UI-3] Tantek Çelik; Florian Rivoal. CSS Basic User Interface Module Level 3 (CSS3 UI) . 7 April 2026. REC. URL: https://www.w3.org/TR/css-ui-3/ [CSS-UI-4] Tab Atkins Jr.; Florian Rivoal. CSS Basic User Interface Module Level 4 . 20 January 2026. WD. URL: https://www.w3.org/TR/css-ui-4/ [CSS-VALUES-3] Tab Atkins Jr.; Elika Etemad. CSS Values and Units Module Level 3 . 22 March 2024. CRD. URL: https://www.w3.org/TR/css-values-3/ [CSS-VALUES-5] Tab Atkins Jr.; Elika Etemad; Miriam Suzanne. CSS Values and Units Module Level 5 . 11 November 2024. WD. URL: https://www.w3.org/TR/css-values-5/ [CSS-VARIABLES-1] Tab Atkins Jr.. CSS Custom Properties for Cascading Variables Module Level 1 . 16 June 2022. CR. URL: https://www.w3.org/TR/css-variables-1/ [CSS-WILL-CHANGE-1] Tab Atkins Jr.. CSS Will Change Module Level 1 . 5 May 2022. CRD. URL: https://www.w3.org/TR/css-will-change-1/ [CSS-WRITING-MODES-3] Elika Etemad; Koji Ishii. CSS Writing Modes Level 3 . 10 December 2019. REC. URL: https://www.w3.org/TR/css-writing-modes-3/ [CSS2] Bert Bos; et al. Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification . 7 June 2011. REC. URL: https://www.w3.org/TR/CSS2/ [CSS3-MEDIAQUERIES] Florian Rivoal. Media Queries Level 3 . 21 May 2024. REC. URL: https://www.w3.org/TR/mediaqueries-3/ [CSS3-NAMESPACE] Elika Etemad. CSS Namespaces Module Level 3 . 20 March 2014. REC. URL: https://www.w3.org/TR/css-namespaces-3/ [MEDIAQUERIES-5] Tab Atkins Jr.; et al. Media Queries Level 5 . 19 February 2026. WD. URL: https://www.w3.org/TR/mediaqueries-5/ [RFC2119] S. Bradner. Key words for use in RFCs to Indicate Requirement Levels . March 1997. Best Current Practice. URL: https://datatracker.ietf.org/doc/html/rfc2119 [SELECTORS-3] Tantek Çelik; et al. Selectors Level 3 . 6 November 2018. REC. URL: https://www.w3.org/TR/selectors-3/ [SELECTORS-4] Elika Etemad; Tab Atkins Jr.. Selectors Level 4 . 22 January 2026. WD. URL: https://www.w3.org/TR/selectors-4/ Non-Normative References [CSS-ALIGN-3] Elika Etemad; Tab Atkins Jr.. CSS Box Alignment Module Level 3 . 30 January 2026. WD. URL: https://www.w3.org/TR/css-align-3/ [CSS-ANIMATIONS-1] David Baron; et al. CSS Animations Level 1 . 2 March 2023. WD. URL: https://www.w3.org/TR/css-animations-1/ [CSS-BREAK-3] Rossen Atanassov; Elika Etemad. CSS Fragmentation Module Level 3 . 4 December 2018. CR. URL: https://www.w3.org/TR/css-break-3/ [CSS-CASCADE-3] Elika Etemad; Tab Atkins Jr.. CSS Cascading and Inheritance Level 3 . 11 February 2021. REC. URL: https://www.w3.org/TR/css-cascade-3/ [CSS-CASCADE-5] Elika Etemad; Miriam Suzanne; Tab Atkins Jr.. CSS Cascading and Inheritance Level 5 . 13 January 2022. CR. URL: https://www.w3.org/TR/css-cascade-5/ [CSS-COLOR-3] Tantek Çelik; Chris Lilley; David Baron. CSS Color Module Level 3 . 18 January 2022. REC. URL: https://www.w3.org/TR/css-color-3/ [CSS-COLOR-ADJUST-1] Elika Etemad; et al. CSS Color Adjustment Module Level 1 . 16 December 2025. CR. URL: https://www.w3.org/TR/css-color-adjust-1/ [CSS-CONDITIONAL-4] Chris Lilley; David Baron; Elika Etemad. CSS Conditional Rules Module Level 4 . 4 September 2025. CRD. URL: https://www.w3.org/TR/css-conditional-4/ [CSS-FONT-LOADING-3] Tab Atkins Jr.. CSS Font Loading Module Level 3 . 6 April 2023. WD. URL: https://www.w3.org/TR/css-font-loading-3/ [CSS-GRID-1] Tab Atkins Jr.; et al. CSS Grid Layout Module Level 1 . 26 March 2025. CRD. URL: https://www.w3.org/TR/css-grid-1/ [CSS-GRID-2] Tab Atkins Jr.; et al. CSS Grid Layout Module Level 2 . 26 March 2025. CRD. URL: https://www.w3.org/TR/css-grid-2/ [CSS-LISTS-3] Elika Etemad; Tab Atkins Jr.. CSS Lists and Counters Module Level 3 . 17 November 2020. WD. URL: https://www.w3.org/TR/css-lists-3/ [CSS-LOGICAL-1] Elika Etemad; Rossen Atanassov. CSS Logical Properties and Values Module Level 1 . 4 December 2025. WD. URL: https://www.w3.org/TR/css-logical-1/ [CSS-MASKING-1] Dirk Schulze; Brian Birtles; Tab Atkins Jr.. CSS Masking Module Level 1 . 5 August 2021. CRD. URL: https://www.w3.org/TR/css-masking-1/ [CSS-NESTING-1] Tab Atkins Jr.. CSS Nesting Module Level 1 . 22 January 2026. WD. URL: https://www.w3.org/TR/css-nesting-1/ [CSS-SCROLL-ANCHORING-1] Tab Atkins Jr.. CSS Scroll Anchoring Module Level 1 . 11 November 2020. WD. URL: https://www.w3.org/TR/css-scroll-anchoring-1/ [CSS-SCROLL-SNAP-1] Matt Rakow; et al. CSS Scroll Snap Module Level 1 . 11 March 2021. CR. URL: https://www.w3.org/TR/css-scroll-snap-1/ [CSS-SCROLLBARS-1] Tantek Çelik; Rossen Atanassov; Florian Rivoal. CSS Scrollbars Styling Module Level 1 . 9 December 2021. CR. URL: https://www.w3.org/TR/css-scrollbars-1/ [CSS-SHAPES-1] Alan Stearns; Rossen Atanassov; Noam Rosenthal. CSS Shapes Module Level 1 . 12 June 2025. CRD. URL: https://www.w3.org/TR/css-shapes-1/ [CSS-SPEECH-1] Léonie Watson; Elika Etemad. CSS Speech Module Level 1 . 14 February 2023. CRD. URL: https://www.w3.org/TR/css-speech-1/ [CSS-TEXT-3] Elika Etemad; Koji Ishii; Florian Rivoal. CSS Text Module Level 3 . 30 September 2024. CRD. URL: https://www.w3.org/TR/css-text-3/ [CSS-TEXT-DECOR-3] Elika Etemad; Koji Ishii. CSS Text Decoration Module Level 3 . 5 May 2022. CRD. URL: https://www.w3.org/TR/css-text-decor-3/ [CSS-TRANSITIONS-1] Chris Marrin; et al. CSS Transitions Module Level 1 . 8 January 2026. WD. URL: https://www.w3.org/TR/css-transitions-1/ [CSS-VIEW-TRANSITIONS-1] Tab Atkins Jr.; Jake Archibald; Khushal Sagar. CSS View Transitions Module Level 1 . 28 March 2024. CRD. URL: https://www.w3.org/TR/css-view-transitions-1/ [CSS-WRITING-MODES-4] Elika Etemad; Koji Ishii. CSS Writing Modes Level 4 . 30 July 2019. CR. URL: https://www.w3.org/TR/css-writing-modes-4/ [CSSOM-1] Daniel Glazman; Emilio Cobos Álvarez. CSS Object Model (CSSOM) . 26 August 2021. WD. URL: https://www.w3.org/TR/cssom-1/ [CSSOM-VIEW-1] Simon Fraser; Emilio Cobos Álvarez. CSSOM View Module . 16 September 2025. WD. URL: https://www.w3.org/TR/cssom-view-1/ [FILTER-EFFECTS-1] Dirk Schulze; Dean Jackson. Filter Effects Module Level 1 . 18 December 2018. WD. URL: https://www.w3.org/TR/filter-effects-1/ [GEOMETRY-1] Sebastian Zartner; Yehonatan Daniv. Geometry Interfaces Module Level 1 . 4 December 2025. CRD. URL: https://www.w3.org/TR/geometry-1/ [MEDIAQUERIES-4] Tab Atkins Jr.; Florian Rivoal. Media Queries Level 4 . 19 February 2026. CRD. URL: https://www.w3.org/TR/mediaqueries-4/ [MOTION-1] Tab Atkins Jr.; Dirk Schulze; Jihye Hong. Motion Path Module Level 1 . 5 November 2024. WD. URL: https://www.w3.org/TR/motion-1/ [RESIZE-OBSERVER-1] Aleks Totic; Greg Whitworth. Resize Observer . 11 February 2020. FPWD. URL: https://www.w3.org/TR/resize-observer-1/ [WEB-ANIMATIONS-1] Brian Birtles; et al. Web Animations . 5 June 2023. WD. URL: https://www.w3.org/TR/web-animations-1/

Related documents

• latn gap#649807
• grek gap#649808
• mong gap#649809
• nkoo gap#649810
• osge osa gap#649811