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CSS current work & how to participate

CSS spec­i­fi­ca­tions

This page contains a list of all completed specifications and drafts by the CSS WG (formerly ‘CSS & FP WG’). If you want to follow the development of CSS, this is the place to start. You have ideas? Contributions? See ‘If you want to help’ on this page.

A specification is not a manual. There is no excuse for badly written drafts and please complain if you find one. But specs do target a specific audience. See fantasai's Understanding the CSS Specifications.. J. David Eisenberg has written another useful How to read W3C specs. Or you can read about ‘modules,’ ‘levels,’ ‘snapshots’ and the CSS process.

What's new? (Also available as Atom news feed.)

Ta­ble of spec­i­fi­ca­tions

Ordered from most to least stable:

Com­pleted Cur­rent Up­com­ing Notes ℹ⃝
CSS Snapshot 2023 NOTE Latest stable CSS ℹ⃝
CSS Snapshot 2022 NOTE ℹ⃝
CSS Snapshot 2021 NOTE ℹ⃝
CSS Snapshot 2020 NOTE ℹ⃝
CSS Snapshot 2018 NOTE ℹ⃝
CSS Snapshot 2017 NOTE ℹ⃝
CSS Snapshot 2015 NOTE ℹ⃝
CSS Snapshot 2010 NOTE ℹ⃝
CSS Snapshot 2007 NOTE ℹ⃝
CSS Color Level 3 REC REC ℹ⃝
CSS Namespaces REC REC ℹ⃝
Selectors Level 3 REC REC ℹ⃝
CSS Level 2 Revision 1 REC REC See Errata ℹ⃝
Media Queries REC REC ℹ⃝
CSS Style Attributes REC REC ℹ⃝
CSS Cascading and Inheritance Level 3 REC REC ℹ⃝
CSS Fonts Level 3 REC REC ℹ⃝
CSS Writing Modes Level 3 REC REC ℹ⃝
CSS Basic User Interface Level 3 REC REC ℹ⃝
CSS Box Model Level 3 REC REC ℹ⃝
CSS Containment Level 1 REC REC ℹ⃝
Stable Cur­rent Up­com­ing Notes ℹ⃝
CSS Backgrounds and Borders Level 3 CRD CR ℹ⃝
CSS Conditional Rules Level 3 CR CR ℹ⃝
CSS Multi-column Layout Level 1 CR PR ℹ⃝
CSS Values and Units Level 3 CR PR ℹ⃝
CSS Flexible Box Layout Level 1 CR PR ℹ⃝
CSS Counter Styles Level 3 CR PR ℹ⃝
Testing Cur­rent Up­com­ing Notes ℹ⃝
CSS Images Level 3 CR CR ℹ⃝
CSS Speech Level 1 CRD CR ℹ⃝
CSS Text Decoration Level 3 CRD CR ℹ⃝
CSS Shapes Level 1 CRD CR ℹ⃝
CSS Masking Level 1 CRD CR ℹ⃝
CSS Text Level 3 CRD CR ℹ⃝
CSS Fragmentation Level 3 CR PR ℹ⃝
CSS Transforms Level 1 CR PR ℹ⃝
CSS Custom Properties for Cascading Variables Level 1 CR CR ℹ⃝
Compositing and Blending Level 1 CR CR ℹ⃝
CSS Syntax Level 3 CRD CR ℹ⃝
CSS Grid Layout Level 1 CRD CR ℹ⃝
CSS Display Level 3 CR CR ℹ⃝
CSS Will Change Level 1 CRD CR ℹ⃝
Media Queries Level 4 CRD CR ℹ⃝
Geometry Interfaces Level 1 CR CR ℹ⃝
CSS Cascading and Inheritance Level 4 CR CR ℹ⃝
CSS Scroll Snap Level 1 CR PR ℹ⃝
CSS Painting API Level 1 CRD CR ℹ⃝
CSS Color Level 4 CRD CR ℹ⃝
CSS Easing Functions Level 1 CRD CR ℹ⃝
CSS Writing Modes Level 4 CR PR ℹ⃝
CSS Grid Layout Level 2 CRD CR ℹ⃝
CSS Scrollbars Styling Level 1 CR PR ℹ⃝
CSS Color Adjustment Level 1 CRD CR ℹ⃝
CSS Conditional Rules Level 4 CR PR ℹ⃝
CSS Cascading and Inheritance Level 5 CR CR ℹ⃝
CSS View Transitions Level 1 CR CR ℹ⃝
Refining Cur­rent Up­com­ing Notes ℹ⃝
CSS Animations Level 1 WD WD ℹ⃝
Web Animations WD WD ℹ⃝
CSS Transitions WD CR ℹ⃝
CSS Box Alignment Level 3 WD WD ℹ⃝
Selectors Level 4 WD WD ℹ⃝
CSS Box Sizing Level 3 WD CR ℹ⃝
CSS Lists and Counters Level 3 WD WD ℹ⃝
CSS Positioned Layout Level 3 WD WD ℹ⃝
Motion Path Level 1 WD WD ℹ⃝
CSS Fonts Level 4 WD WD ℹ⃝
CSS Logical Properties and Values Level 1 WD WD ℹ⃝
Revising Cur­rent Up­com­ing Notes ℹ⃝
CSS Paged Media Level 3 WD WD ℹ⃝
CSSOM View WD WD ℹ⃝
CSS Ruby Annotation Layout Level 1 WD WD ℹ⃝
CSS Object Model (CSSOM) WD WD ℹ⃝
CSS Overflow Level 3 WD WD ℹ⃝
CSS Font Loading Level 3 WD WD ℹ⃝
CSS Scoping Level 1 FPWD WD ℹ⃝
CSS Pseudo-Elements Level 4 WD WD ℹ⃝
CSS Image Values and Replaced Content Level 4 WD WD ℹ⃝
CSS Overflow Level 4 WD WD ℹ⃝
CSS Text Decoration Level 4 WD WD ℹ⃝
Resize Observer FPWD WD ℹ⃝
Media Queries Level 5 WD WD ℹ⃝
CSS Box Sizing Level 4 WD WD ℹ⃝
Exploring Cur­rent Up­com­ing Notes ℹ⃝
CSS Backgrounds and Borders Level 4 FPWD ℹ⃝
CSS Viewport Level 1 WD WD ℹ⃝
CSS Exclusions WD WD ℹ⃝
Filter Effects Level 1 WD WD ℹ⃝
CSS Generated Content for Paged Media WD WD ℹ⃝
CSS Page Floats FPWD WD ℹ⃝
CSS Template Layout NOTE NOTE ℹ⃝
CSS Line Grid WD WD ℹ⃝
CSS Regions WD WD ℹ⃝
CSS Table Level 3 WD WD ℹ⃝
CSS Inline Layout Level 3 WD WD ℹ⃝
CSS Round Display Level 1 WD WD ℹ⃝
CSS Basic User Interface Level 4 WD WD ℹ⃝
CSS Text Level 4 WD WD ℹ⃝
CSS Properties and Values API Level 1 WD WD ℹ⃝
CSS Typed OM Level 1 WD WD ℹ⃝
CSS Rhythmic Sizing Level 1 FPWD WD ℹ⃝
CSS Fill and Stroke Level 3 FPWD WD ℹ⃝
CSS Layout API Level 1 FPWD WD ℹ⃝
CSS Values and Units Level 4 WD WD ℹ⃝
CSS Shadow Parts FPWD WD ℹ⃝
CSS Fragmentation Level 4 FPWD WD ℹ⃝
CSS Spatial Navigation Level 1 WD WD ℹ⃝
CSS Overscroll Behavior Level 1 FPWD WD ℹ⃝
CSS Animation Worklet API FPWD WD ℹ⃝
CSS Containment Level 2 WD WD ℹ⃝
CSS Scroll Anchoring Level 1 WD WD ℹ⃝
CSS Color Level 5 WD WD ℹ⃝
CSS Transforms Level 2 WD WD ℹ⃝
CSS Box Model Level 4 WD WD ℹ⃝
CSS Custom Highlight API Level 1 WD WD ℹ⃝
CSS Fonts Level 5 WD WD ℹ⃝
CSS Nesting WD WD ℹ⃝
CSS Cascading and Inheritance Level 6 WD WD ℹ⃝
CSS Conditional Rules Level 5 FPWD WD ℹ⃝
CSS Containment Level 3 WD WD ℹ⃝
Scroll-driven Animations WD WD ℹ⃝
CSS Animations Level 2 FPWD WD ℹ⃝
Web Animations Level 2 FPWD WD ℹ⃝
CSS Transitions Level 2 FPWD WD ℹ⃝
CSS Anchor Positioning WD WD ℹ⃝
Rewriting Cur­rent Up­com­ing Notes ℹ⃝
CSS Generated Content Level 3 WD WD ℹ⃝
Abandoned Cur­rent Up­com­ing Notes ℹ⃝
CSS Level 1 SPSD ℹ⃝
CSS Mobile Profile 2.0 NOTE ℹ⃝
Non-element Selectors NOTE ℹ⃝
The CSS 'Reader' Media Type NOTE ℹ⃝
CSS Presentation Levels NOTE ℹ⃝
CSS TV Profile 1.0 NOTE ℹ⃝
CSS Marquee NOTE ℹ⃝
Behavioral Extensions to CSS NOTE ℹ⃝
Fullscreen NOTE ℹ⃝
Preview of CSS Level 2 FPWD NOTE ℹ⃝
Worklets Level 1 NOTE ℹ⃝

Some related specifications by other Working Groups:

Title Cur­rent Notes
Predefined Counter Styles NOTE I18N WG
CSS Techniques for Web Content Accessibility Guidelines 1.0 NOTE WCAG WG
Associating Style Sheets with XML documents 1.0 (Second Edition) REC XML Core WG
Web App Manifest WD Web Applications WG
Selectors API Level 1 REC Web Applications WG
DOM CR WHAT WG

Two old specifications by the Web Applications WG, The 'view-mode' Media Feature and Selectors API Level 2, have been replaced by Web App Manifest and DOM, respectively.

Indexes of properties & descriptors

The CSS Snapshot includes an index of standard and stable properties, along with pseudo-classes & pseudo-elements and @-rules.

The CSS WG provides an alphabetical list of all properties & descriptors in editors' drafts.

People who are reviewing CSS drafts might also be interested in these indexes that include both official and editors' drafts: properties [HTML] [TSV] [XML] [JSON] and descriptors [HTML] [TSV] [XML] [JSON].

Ex­pla­na­tion of col­ors & status codes

W3C indicates the maturity of specifications by a status code. The CSS working group uses the following, from least to most stable:

Ab­bre­vi­a­tion Full name
FPWD First Public Working Draft
WD Working Draft
CR Candidate Recommendation
CRD Candidate Recommendation Draft
PR Proposed Recommendation
REC Recommendation
SPSD Superseded Recommendation

The following code indicates a document that is not intended to become a standard:

Ab­bre­vi­a­tion Full name
NOTE Working Group Note

The names are defined in section 6 of the W3C process document. A REC is what is normally referred to as a ‘standard.’ W3C encourages everyday use starting from CR.

The informal stability levels used to group the specs are defined in this 2007 description of CSS stability levels.

If you want to help

Everybody can take part in the discussions on the archived mailing list www-style@w3.org. You can subscribe yourself. This is the preferred place for discussions, because the members of the working group will see them. Please, don't use this list for questions of the type How do I… Use comp. infosystems. www. authoring. stylesheets ("ciwas") or see ‘Learning CSS’.

On the mailing list, you will be talking to many people, many very busy people. Before you post, please, search the archive to see if your great idea has maybe already been discussed. Follow the usual netiquette and W3C's policies on spam, attachments, etc.

If you are sending comments on a specific CSS module, please prefix the subject of your message with the appropriate spec code (given in the ‘Status of this document’ section) in brackets, e.g. ‘[css3-flexbox] error in margin calculations’. This will help the editors find and track your comments.

Laurens Holst (a.k.a. ‘Grauw’) maintains an FAQ for www-style. (For additions, please, contact Laurens directly. Laurens is not associated with W3C.)

You can also raise issues via GitHub. Github contains copies of the editors' drafts of the CSS specifications and ‘Houdini’ APIs.

Birkir Gunnarsson wrote a helpful guide Mastering GitHub with a screen reader, part 1.

If you work for a W3C member organization, you can also join the CSS working group and come to its meetings. To participate, you need to commit to (on average) 1 day per week. Contact me (Bert Bos) or your organization's W3C contact person. The group's minutes are public and posted on the CSS WG blog.

There are many ways to keep up to date with new publications by the CSS WG. The ‘What's new?’ section above shows the most recent drafts and it also has an Atom feed. Publications are announced on the CSS WG's blog and its Atom feed, and the group's Mastodon account. First drafts from all W3C working groups appear on the public-review-announce mailing list and its RSS feed. The latest publications from all W3C working groups are at the top of the Technical Reports page, which also has an RSS feed.

About the test suites

The CSS working group intends to spend a lot of time on developing the CSS test suites along with the CSS specifications. By providing a test suite for each module as soon as the module is published, we hope not only that CSS implementations will conform to the specification much earlier, but also that people will have an easier time understanding the formal text of the spec.

The test suites have their own archived mailing list public-css-testsuite@w3.org. Please send error reports, test case submissions, and any other questions and comments about the CSS test suites there. Elika Etemad maintains the CSS Testing Wiki with more info for contributors.

Raising issues via GitHub is also possible: see the Web-platform tests repository.

Mark-up con­ven­tions

The source mark-up of the specifications follows certain conventions (which is useful for automatic processing).

Bert Bos, style activity lead
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Last updated Fri 15 Mar 2024 11:23:45 AM UTC

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