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(similar intro as DOM)
(finished most of the rest of the things, a few things dropped, drop unmaintained dashboard & old meta bugs, forward to GeckoGoalsfor2021#CSS for current CSS priorities)
 
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= CSS =
= CSS =
== Priorities ==
== Priorities ==
The following CSS specs/proposals are a priority.
* See [[GeckoGoalsfor2021#CSS]]
 
=== 2018 Priorities ===
These are *in progress* 2018 Priorities for CSS features in Firefox.
* Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1424418
* Some public input: https://twitter.com/t/status/939273644043366400
* Subsequently discussed by the Platform Layout team at [[Yallhands]] in Austin, Texas (further adjustments are likely)
 
==== Close to shipping ====
These features have implementations that are already well in progress and thus it is a priority to finish them and ship.
 
===== Variable Fonts =====
<span id="Fonts_Level_4">Fonts Level 4</span> for Variable Fonts support in particular:
* Bugzilla for Variable Fonts: https://bugzilla.mozilla.org/show_bug.cgi?id=1302685
**  unlikely mobile impact, do any mobile platforms ship a variable font at all?
* [https://drafts.csswg.org/css-fonts-4/ Fonts 4] ([https://www.w3.org/TR/css-fonts-4/ TR] FPWD 2017), [https://bugzilla.mozilla.org/show_bug.cgi?id=css-fonts-4 metabug]
Reprioritize Fonts Level 4 accordingly once we have Variable Fonts.
 
===== Shapes =====
* [https://drafts.csswg.org/css-shapes/ CSS Shapes] ([https://www.w3.org/TR/css-shapes/ TR] CR 2014, another CR was expected in 2017) [https://bugzilla.mozilla.org/show_bug.cgi?id=1040714 metabug]
** [https://bugzilla.mozilla.org/show_bug.cgi?id=1098939 shape-outside]
* would make mobile use-cases more compelling and closer to native apps
 
==== Critical Fixes ====
Critical fixes to features or larger specs we already support (more important than new features in general)
* [https://drafts.csswg.org/css-scroll-anchoring/ Scroll Anchoring] (ED): https://bugzilla.mozilla.org/show_bug.cgi?id=1305957
* [https://bugzilla.mozilla.org/show_bug.cgi?id=1398482 Drop grid- prefix from various properties] (including grid-gap. for CSS Grid)
** [https://twitter.com/regocas/status/960631270140203008]
* List from DevRel kept here: http://mozdevs.github.io/devrel-dashboard/ in CSS and Layout sections
 
==== Multi-column ====
* [https://drafts.csswg.org/css-multicol/ CSS Multi-column Layout] ([https://www.w3.org/TR/css3-multicol/ TR WD]), [https://bugzilla.mozilla.org/show_bug.cgi?id=684062 metabug]
** unprefixing, [https://bugzilla.mozilla.org/show_bug.cgi?id=616436 column-span], a11y bug hack removal, column-break
** Alias page-break-* to break-*: https://bugzilla.mozilla.org/show_bug.cgi?id=775618
** Low to no mobile impact, possible tablet impact
(Jen has a demo of bugs / test page at http://labs.jensimmons.com/examples/multicolumn-3-bug-demo.html)
 
==== Values and Units 3 ====
[https://www.w3.org/TR/css3-values/ CSS Values and Units Module Level 3] (CR) [https://bugzilla.mozilla.org/show_bug.cgi?id=741643 metabug]
* [ ] calc() function in particular. [https://bugzilla.mozilla.org/show_bug.cgi?id=1376206 metabug]
* re-prioritize Values and Units 3 once calc fixes have landed.
* [ ] attr function (at risk) — very useful in combination with CSS Shapes, in the context of a CMS
 
==== Scroll Snap update ====
* [https://drafts.csswg.org/css-scroll-snap-1/ Scroll Snap] ([https://www.w3.org/TR/css-scroll-snap-1/ CR]), [https://bugzilla.mozilla.org/show_bug.cgi?id=1231777 metabug]
** Fix [https://bugzilla.mozilla.org/buglist.cgi?quicksearch=%22scroll+snap%22 related bugs] - update to latest version of the spec
** [https://caniuse.com/#feat=css-snappoints Safari 11 / iOS11+ supports], [https://twitter.com/rachelandrew/status/969590800966455301 Safari-only demo]
** likely medium impact on mobile
 
==== Media Queries ====
* <span id="Media_Queries_4">[https://drafts.csswg.org/mediaqueries-4/ Media Queries 4]</span> (note: [https://drafts.csswg.org/mediaqueries-4/#changes-2012 new features in 4]), [https://bugzilla.mozilla.org/show_bug.cgi?id=1312621 metabug], specifically:
** [https://drafts.csswg.org/mediaqueries-4/#mf-interaction interaction features]  [https://bugzilla.mozilla.org/show_bug.cgi?id=1035774 #1035774] per [https://bugzilla.mozilla.org/show_bug.cgi?id=1312621#c1 2017: supported in Microsoft Edge, Chrome, Safari, Opera, and Android browser]
* [https://drafts.csswg.org/mediaqueries-5/ Media Queries 5], [https://bugzilla.mozilla.org/show_bug.cgi?id=1434491 metabug], specifically:
** [https://drafts.csswg.org/mediaqueries-5/#prefers-reduced-motion prefers-reduced-motion] [https://bugzilla.mozilla.org/show_bug.cgi?id=1365045 #1365045] per [https://bugs.webkit.org/show_bug.cgi?id=163250 supported in WebKit]
* Re-evaluate MQ4/5 prioritization after interaction and prefers-reduced-motion features are implemented.
** full support of numerical comparators (&lt;, &lt;=, =>, >)
** expansion of negation syntax (and, or, not)
** [https://logs.csswg.org/irc.w3.org/css/2017-08-02/#e841291 2017-08-02 CSSWG resolved to take to CR]
** Also [https://drafts.csswg.org/mediaqueries-5/#prefers-reduced-motion prefers-reduced-motion] from Level 5 ([https://bugzilla.mozilla.org/show_bug.cgi?id=1365045 #1365045])
** watch for mobile uptake, especially for mobile layout
 
=== 2018 Medium Priorities ===
2018 medium priorities are "maybe" items that we're not sure we can get to in 2018, but would really like to (had a lot of interest during [[yallhands]]).
 
==== Containment ====
* [https://drafts.csswg.org/css-containment/ CSS Containment Module Level 1] ([https://www.w3.org/TR/2017/WD-css-contain-1-20170221/ FPWD 2017]) 'contain' property, size/layout, style, paint. [https://bugzilla.mozilla.org/show_bug.cgi?id=1150081 metabug]
** potential impact for mobile layouts, mobile web apps
** [http://caniuse.com/containment Chrome shipped in 61]
 
==== Grid Level 2 ====
Grid Level 2 AKA subgrid (use-cases, a11y implications)
* [https://drafts.csswg.org/css-grid-2/ CSS Grid level 2] (2018-01-31 Resolved to go FPWD) specifically [https://bugzilla.mozilla.org/buglist.cgi?quicksearch=subgrid for subgrid]
* doing some exploratory implementing, design may (hopefully likely) change accordingly
* see also for quick use-cases / tutorial:
** http://fantasai.inkedblade.net/style/discuss/subgrid-markup/
* medium mobile potential impact, different grid layouts for different responsive use-cases
 
==== Container Queries Prerequisites ====
There's a lot of anecdotal demand for Container Queries / Element Queries. See replies here:
* https://twitter.com/t/status/939273644043366400
* https://twitter.com/t/status/955560233144905733 (strong interest, 100+ retweets!)
 
We should at least figure out what features / bug fixes we would need to address to even consider something like Container Queries (which we should also give input on)
* [https://github.com/WICG/cq-usecases WICG cq-usecases effort] ([https://github.com/ResponsiveImagesCG/cq-usecases/issues view open issues] to help contribute)
* one proposal: https://tomhodgins.github.io/element-queries-spec/element-queries.html
 
=== 2018 Lower Priorities ===
Features or areas that are lower priority based on a number of factors.
 
==== CSS Images 3 ====
* [https://drafts.csswg.org/css-images-3/ CSS Images Module Level 3], ([https://www.w3.org/TR/css3-images/ 2012 CR]), [https://bugzilla.mozilla.org/show_bug.cgi?id=703431 metabug]
* [https://bugzilla.mozilla.org/show_bug.cgi?id=546052 cross-fade()] -- particularly relevant when animating between images
* [https://bugzilla.mozilla.org/show_bug.cgi?id=1358327 image-orientation:none]
** possible mobile use-case: photos, just taken on device
* [https://bugzilla.mozilla.org/show_bug.cgi?id=856337 image-rendering: pixelated]
** mobile use-case: displaying QR codes
* [https://bugzilla.mozilla.org/show_bug.cgi?id=1288941 position syntax in radial-gradient()]
* low to medium mobile impact
 
==== Box Alignment ====
* [https://drafts.csswg.org/css-align/ CSS Box Alignment] ([https://www.w3.org/TR/css-align-3/ WD]), [https://bugzilla.mozilla.org/show_bug.cgi?id=1105570 metabug]
** all properties for blocks (e.g. [https://bugzilla.mozilla.org/show_bug.cgi?id=1105571 1105571])
** and some details for flexbox (see metabug 1105570 Depends on)
** spec CR depends on resolving [https://github.com/w3c/csswg-drafts/labels/css-align-3 open css-align-3 issues]
* unlikely mobile impact (mobile layouts more likely to use flexbox with box alignment properties)
 
==== Inline Layout ====
* [https://drafts.csswg.org/css-inline/ CSS Inline Layout Module Level 3] ([https://www.w3.org/TR/css-inline-3/ TR WD]), [https://bugzilla.mozilla.org/show_bug.cgi?id=1312611 metabug]
** focusing for now on CSS Initial-letter related features ([https://bugzilla.mozilla.org/show_bug.cgi?id=1273019 initial-letter * metabug])
*** one (implementation design) blocker issue: https://github.com/w3c/csswg-drafts/issues/743
 
==== Scrollbar Styling ====
Spec in editor's draft - many requests for this
* https://drafts.csswg.org/css-scrollbars-1/
* no to low if any mobile impact - mobile UIs typically do not display scrollbars, or completely build their own.
 
==== text-decoration-skip ====
* Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=812990
* parity with Chrome
 
==== SVG properties in CSS ====
This bit from SVG2:
* [https://bugzilla.mozilla.org/show_bug.cgi?id=1383650 1383650: Implement SVG geometry properties in CSS]
 
==== Sizing ====
[https://drafts.csswg.org/css-sizing-3/ CSS Intrinsic & Extrinsic Sizing Module Level 3] ([https://www.w3.org/TR/css-sizing-3/ TR] WD) [https://bugzilla.mozilla.org/show_bug.cgi?id=1312587 metabug]
* intrinsic size keywords: fix [https://bugzilla.mozilla.org/show_bug.cgi?id=567039 #567039] & [https://bugzilla.mozilla.org/show_bug.cgi?id=1055887 #1055887], and unprefix ([https://bugzilla.mozilla.org/show_bug.cgi?id=1322780 #1322780]
* medium mobile impact from height related properties
 
==== Motion Path ====
* [https://drafts.fxtf.org/motion-1/ Motion Path Module Level 1] ([https://www.w3.org/TR/motion-1/ TR] WD 2017), [https://bugzilla.mozilla.org/show_bug.cgi?id=1186329 meta bug]
** Blink: [https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/N4o2MoV1zuw 2015-06-09 intent ship]; [https://codepen.io/danwilson/post/css-motion-paths-2016 Chrome 56+]
* unlikely mobile impact, do any mobile sites even try to use this? or is it just cosmetic?
 
==== CSS Color Level 4 ====
[https://drafts.csswg.org/css-color-4/ CSS Color Module Level 4] (ED), [https://bugzilla.mozilla.org/show_bug.cgi?id=1352753 metabug]
* Color improvements (wide gamut, color correction, note CSS color correction preffed off)
* low mobile impact (variable lighting anyway, users use of filters)
Implement correct color management of CSS colors (which is really earlier levels of CSS color).
 
==== Better Print Support ====
Start looking at what specs and features would significantly improve print support. Much of this is testing and bugfixing edgecases of existing features, some of it may require or benefit from new specs/features.
* [https://drafts.csswg.org/css-page-3/ CSS Paged Media Module Level 3] ([https://www.w3.org/TR/css3-page/ old 2013 WD]) [https://bugzilla.mozilla.org/show_bug.cgi?id=286443 metabug]
More specs / features in particular TBD.
 
==== Houdini ====
* [[CSS/Houdini|CSS Houdini]] - see inside for Houdini implementation thoughts/plan
* parity with: [https://developers.google.com/web/updates/2018/01/paintapi Chrome 65 supporting CSS Paint API by default]
 
=== Actively Implementing ===
Beyond the above priorities, we should continue to actively implement, fix bugs on the following:
 
* [[Stylo]] ([https://bugzilla.mozilla.org/show_bug.cgi?id=1243581 metabug])
 
==== Flexbox ====
Mozilla has a pretty solid complete [https://www.w3.org/TR/css-flexbox-1/ Flexbox] (W3C CR, just waiting on feature-interaction tests to go PR) implementation. We are working on some fixes to make it even better, e.g.
* [https://bugzilla.mozilla.org/show_bug.cgi?id=1055888 Metabug for to-be-implemented spec changes]
 
==== Grid ====
* [https://drafts.csswg.org/css-grid/ CSS Grid] ([https://www.w3.org/TR/2017/CR-css-grid-1-20170509/ CR]) [https://bugzilla.mozilla.org/show_bug.cgi?id=1312610 metabug]
** [https://bugzilla.mozilla.org/buglist.cgi?quicksearch=%5Bcss-grid%5D lots of work]
 
==== 3D Transforms ====
* 3D Transform interop / spec changes, [https://bugzilla.mozilla.org/buglist.cgi?quicksearch=%223d%20transform%22 3D transform bugs]
 
==== Masking ====
* [https://drafts.fxtf.org/css-masking-1/ CSS Masking] (W3C [https://www.w3.org/TR/css-masking-1/ CR]), [https://bugzilla.mozilla.org/show_bug.cgi?id=1312613 metabug]
** another clip-path ticket — path(): https://bugzilla.mozilla.org/show_bug.cgi?id=1246764
 
==== Text Decoration ====
[https://drafts.csswg.org/css-text-decor-3/ CSS Text Decoration Module Level 3] ([https://www.w3.org/TR/2013/CR-css-text-decor-3-20130801/ 2013 CR]) ([https://bugzilla.mozilla.org/show_bug.cgi?id=1221864 metabug]), e.g.:
* focusing on text-decoration-skip https://bugzilla.mozilla.org/show_bug.cgi?id=812990
* text-emphasis ([https://bugzilla.mozilla.org/show_bug.cgi?id=1225012 remaining bugs])
* [https://bugzilla.mozilla.org/show_bug.cgi?id=770780 text-underline-position]
* What else left for this module? (JS)
** See "Depends on" in [https://bugzilla.mozilla.org/show_bug.cgi?id=1221864 metabug 1221864] (TÇ)
 
==== Writing Modes ====
[https://drafts.csswg.org/css-writing-modes-3/ CSS Writing Modes Level 3] ([https://www.w3.org/TR/css-writing-modes/ 2015 CR]) ([https://bugzilla.mozilla.org/show_bug.cgi?id=145503 metabug])
* [https://logs.csswg.org/irc.w3.org/css/2017-08-04/#e847806 2017-08-04 CSSWG Resolved] to publish an updated CR
 
==== Fonts Level 3 ====
Wrap-up the few remaining bugs, or declare that we're done (e.g. font-variant as a descriptor?)
* [https://drafts.csswg.org/css-fonts-3/ Fonts 3], [https://bugzilla.mozilla.org/show_bug.cgi?id=651693 metabug]
 
==== Under the hood and related ====
* Intersection observer ([https://groups.google.com/forum/#!searchin/mozilla.dev.platform/Intersection$20observer%7Csort:relevance/mozilla.dev.platform/YdKTMvQygl0/etZvkSkeDQAJ Intent to ship thread])
* Resize observer (intent to implement coming)
* [https://w3c.github.io/web-animations/ Web Animations API] ([https://bugzilla.mozilla.org/show_bug.cgi?id=875219 metabug])
 
=== Evaluating ===
==== Font Rendering Controls ====
[https://tabatkins.github.io/specs/css-font-display/ CSS Font Rendering Controls Module Level 1] (ED)
* focusing on font-display descriptor https://bugzilla.mozilla.org/show_bug.cgi?id=1317445 (implemented behind a flag, other browsers too)
 
==== Font Loading ====
[https://www.w3.org/TR/css-font-loading/ CSS Font Loading Module Level 3] https://developer.mozilla.org/en-US/docs/Web/API/CSS_Font_Loading_API shipped in 41
* CSS Font Loading Improvements, Multiple bugs
 
==== Other ====
* font inflation removed
* CSS Transform properties (shorthands)
 
=== Related HTML5 ===
[[HTML5]] layout and presentation related work:
* [https://bugzilla.mozilla.org/show_bug.cgi?id=1149357 srcset intrinsic size]
* ...
 
=== Recent CRs ===
==== Cascading and Inheritance ====
* [https://drafts.csswg.org/css-cascade-3/ CSS Cascading and Inheritance Level 3] ([https://www.w3.org/TR/css-cascade-3/ CR]), [https://bugzilla.mozilla.org/show_bug.cgi?id=1312619 metabug]
** [https://drafts.csswg.org/css-cascade-3/#changes-2 New features since CSS2.x]
*** scoped styles, animations, and transitions in the cascade.
 
=== Upcoming CRs ===
These CRs are expected in 2017:
 
For all potential CRs:
* Which browsers have openly announced implementations or intent to implement? (links?)
 
* Box Alignment (see above)
 
==== Text Level 3 ====
* [https://drafts.csswg.org/css-text/ Text] (need list of [https://www.w3.org/Style/CSS/Tracker/actions/799 changes since CSS 2.1]), [https://bugzilla.mozilla.org/show_bug.cgi?id=104960 metabug]
 
==== Selectors 4 ====
[https://drafts.csswg.org/selectors-4/ Selectors 4] (need list of [https://github.com/w3c/csswg-drafts/issues/622 changes since 3]), [https://bugzilla.mozilla.org/show_bug.cgi?id=693083 metabug]
* No explicit dependency on Stylo, just lower priority
* Selectors4 remaining features
** CSS ::selection fixes + unprefixing
** ... remaining new features? (JS)
 
=== Shipping Soon ===
As the above priorities get implemented, moving down here to note we're waiting for them to ship.
 
==== Image Values and Replaced Content ====
[https://drafts.csswg.org/css-images-4/] (CR)
* image() function
* [ ] xywh fragment syntax
 
==== Style sheet APIs for Add-ons ====
* style sheet APIs in add-ons SDK / loading async APIs (to be handled by stylo)
 
==== Filter Effects Level 2 ====
* [https://drafts.fxtf.org/filters-2/#BackdropFilterProperty Filter Effects Module Level 2: backdrop-filter]
** [https://bugzilla.mozilla.org/show_bug.cgi?id=1178765 backdrop-filter bug] (caniuse: only Safari supports)
** also on Trello Future Backlog
 
==== Device Adaptation ====
[https://drafts.csswg.org/css-device-adapt/ CSS Device Adaptation Module Level 1] ([https://www.w3.org/TR/css-device-adapt-1/ WD])


== properties ==
== properties ==
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* ...
* ...


=== in development ===
== Previously ==
CSS properties which have not yet made it to a Candidate Recommendation (or later), or are only implemented in the wild in prefixed form.
* 2019 Metabug for CSS Priorities: https://bugzilla.mozilla.org/show_bug.cgi?id=1424418
 
* 2018 public input: https://twitter.com/t/status/939273644043366400
==== new pseudo-classes ====
** Subsequently discussed by the Platform Layout team at [[Yallhands]] and by the Layout team at [[Mozlando2018]]
* ...
* [[CSS/:autofill|:autofill]]
* ...
 
==== new properties ====
* ...
* [[CSS/text-size-adjust|text-size-adjust]] (-moz-, -ms-, -webkit-)
* ...


== See Also ==
== See Also ==
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* [[Platform]]
* [[Platform]]
* [https://developer.mozilla.org/en/CSS MDN: CSS home page]
* [https://developer.mozilla.org/en/CSS MDN: CSS home page]
* [http://mozdevs.github.io/devrel-dashboard/ Mozilla DevRel Dashboard] - dynamic overview of [META] and other high level bugs in [[CSS]], [[DOM]], [[DevTools]], [[MDN]], [[Toolkit]], etc.
* [https://wiki.csswg.org/ CSS Working Group Wiki]
* [https://wiki.csswg.org/ CSS Working Group Wiki]

Latest revision as of 17:51, 20 April 2021

CSS is short for Cascading Style Sheets (CSS), and typically includes the full set of Selectors, CSS properties, values, and @-rules supported by browsers.

CSS is one of several web standards.

For documentation on CSS, how to develop for it, use various properties, see:

CSS

Priorities

properties

Please add subpages for each (unprefixed) CSS property in alphabetical order.

Previously

See Also

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