CSS

====CSS 4====
{{redirect|CSS4}}

[[File:CSS Standardization - The State of the Web.webm|thumb|[[Jen Simmons]] discussing the state of CSS in 2019, as several CSS{{nbsp}}4 modules were being advanced]]
There is no single, integrated CSS4 specification,<ref>{{cite web|last=Atkins|first=Tab Jr.|title=A Word About CSS4|url=https://www.xanthir.com/b4Ko0|access-date=18 October 2012|archive-url=https://web.archive.org/web/20121031194751/https://www.xanthir.com/b4Ko0|archive-date=31 October 2012|url-status=live}}</ref> because the specification has been split into many separate modules which level independently.

Modules that build on things from CSS Level 2 started at Level 3. Some of them have already reached Level 4 or are already approaching Level 5. Other modules that define entirely new functionality, such as [[Flexbox]],<ref>{{cite web|url=https://www.w3.org/TR/css3-flexbox/|title=CSS Flexible Box Layout Module Level 1|publisher=W3C|date=19 November 2018|access-date=18 October 2012|archive-url=https://web.archive.org/web/20121019153636/https://www.w3.org/TR/css3-flexbox/|archive-date=19 October 2012|url-status=live}}</ref> have been designated as Level 1 and some of them are approaching Level 2.

The CSS Working Group sometimes publishes "Snapshots", a collection of whole modules and parts of other drafts that are considered stable enough to be implemented by browser developers. So far, five such "best current practices" documents have been published as Notes, in 2007,<ref>{{cite web |url=https://www.w3.org/TR/css-beijing/ |title=Cascading Style Sheets (CSS) Snapshot 2007 |date=12 May 2011 |access-date=18 July 2016 |archive-url=https://web.archive.org/web/20160808144255/https://www.w3.org/TR/css-beijing/ |archive-date=8 August 2016 |url-status=live }}</ref> 2010,<ref>{{cite web |url=https://www.w3.org/TR/css-2010/ |title=Cascading Style Sheets (CSS) Snapshot 2010 |date=12 May 2011 |access-date=3 March 2011 |archive-url=https://web.archive.org/web/20110316103250/https://www.w3.org/TR/css-2010/ |archive-date=16 March 2011 |url-status=live }}</ref> 2015,<ref>{{cite web |url=https://www.w3.org/TR/css-2015/ |title=CSS Snapshot 2015 |date=13 October 2015 |website=W3C |access-date=13 February 2017 |archive-url=https://web.archive.org/web/20170127073733/https://www.w3.org/TR/css-2015/ |archive-date=27 January 2017 |url-status=live }}</ref> 2017,<ref>{{cite web |url= https://www.w3.org/TR/css-2017/ |website=W3C  |title= CSS Snapshot 2017 |date= 31 January 2017 |access-date= 13 February 2017 |archive-url= https://web.archive.org/web/20170213164514/https://www.w3.org/TR/css-2017/ |archive-date= 13 February 2017 |url-status= live }}</ref> and 2018.<ref>{{cite web |url=https://www.w3.org/TR/css-2018/ |title=CSS Snapshot 2018 |date=22 January 2019 |website=W3C  |access-date=2 January 2019 |archive-url=https://web.archive.org/web/20190201162518/https://www.w3.org/TR/css-2018/ |archive-date=1 February 2019 |url-status=live }}</ref>

Since these specification snapshots are primarily intended for developers, there has been a growing demand for a similar versioned reference document targeted at authors, which would present the state of interoperable implementations as meanwhile documented by sites like Can I Use...<ref name="caniuse">{{cite web|url=https://caniuse.com/#cats=CSS|website=Can I Use… Support tables for HTML5, CSS3, etc. |title=CSS |access-date=2019-01-26|archive-url=https://web.archive.org/web/20180219074228/https://caniuse.com/#cats=CSS|archive-date=2018-02-19|url-status=live}}</ref> and the MDN Web Docs.<ref name="mdn">{{cite web|url=https://developer.mozilla.org/docs/Web/CSS|website=MDN Web Docs |title=CSS|date=21 July 2023 |url-status=live |archive-url=https://web.archive.org/web/20231126230858/https://developer.mozilla.org/en-US/docs/Web/CSS |archive-date= Nov 26, 2023 }}</ref> A W3C Community Group has been established in early 2020 in order to discuss and define such a resource.<ref name="css4">{{cite web|url=https://www.w3.org/community/css4/|title=Call for Participation in CSS4 Community Group |website=W3C |date=24 February 2020 |access-date=2020-02-27|archive-url=https://web.archive.org/web/20230210062151/https://www.w3.org/community/css4/2020/02/24/call-for-participation-in-css4-community-group/ |archive-date=Feb 10, 2023 |url-status=live}}</ref> The actual kind of [[software versioning|versioning]] is also up to debate, which means that the document, once produced, might not be called "CSS4".