CSS

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:

• https://developer.mozilla.org/en/CSS

CSS

Priorities

In Progress: Restructuring this page for 2021.

To Be Updated

The following sections of this page are out of date as of 2021-04-13 and kept only for historical purposes as part of restructuring this page for 2020.

If you have questions about any specific CSS feature, please click through to its bug/metabug and check its actual status there.

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• DevRel List: http://mozdevs.github.io/devrel-dashboard/ in CSS and Layout sections
• Metabug for 2019 CSS Priorities: https://bugzilla.mozilla.org/show_bug.cgi?id=1424418

Re-evaluate

Houdini

• CSS Houdini - see inside for Houdini implementation thoughts/plan
• working towards (longer-term)
  • Properties & Values API
  • prerequisites for Paint API (Worklets, parts of Typed OM)
  • parity with: Chrome 65 supporting CSS Paint API by default
  • re-evaluate priority of rest of Houdini at this point and re-sort accordingly

Box Alignment

• CSS Box Alignment (WD), metabug
  • all properties for blocks (e.g. 1105571)
  • and some details for flexbox (see metabug 1105570 Depends on)
  • spec CR depends on resolving open css-align-3 issues
• unlikely mobile impact (mobile layouts more likely to use flexbox with box alignment properties)

Conic Gradients

• CSS Images Module Level 4: conic-gradient() (WG)
• Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1175958
• Supported in Chrome 69+, Opera 56+, Android, and in Safari Technology Preview

Multi-column

• CSS Multi-column Layout (TR WD), metabug
  • unprefixing, column-span, a11y bug hack removal, column-break
  • 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)

CSS Images 3

• CSS Images Module Level 3, (2012 CR), metabug
• cross-fade() -- particularly relevant when animating between images
• image-orientation:none
  • possible mobile use-case: photos, just taken on device
• image-rendering: pixelated
  • mobile use-case: displaying QR codes
• position syntax in radial-gradient()
• low to medium mobile impact

SVG properties in CSS

This bit from SVG2:

• 1383650: Implement SVG geometry properties in CSS

Motion Path

• Motion Path Module Level 1 (TR WD 2017), meta bug
  • Blink: 2015-06-09 intent ship; Chrome 56+
• unlikely mobile impact, do any mobile sites even try to use this? or is it just cosmetic?

CSS Color Level 4

CSS Color Module Level 4 (ED), 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.

• CSS Paged Media Module Level 3 (old 2013 WD) metabug

More specs / features in particular TBD.

Other

• font inflation removed
• CSS Transform properties (shorthands)

properties

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

• ...
• overflow
• ...
• text-overflow
• ...

Previously

• 2018 public input: https://twitter.com/t/status/939273644043366400
  • Subsequently discussed by the Platform Layout team at Yallhands and by the Layout team at Mozlando2018

See Also

• CSS/
• CSS/:autofill
• CSS/Houdini
• CSS/text-overflow
• CSS/text-size-adjust

• CSS3
• HTML5
• DOM
• Standards
• Platform
• MDN: CSS home page
• Mozilla DevRel Dashboard - dynamic overview of [META] and other high level bugs in CSS, DOM, DevTools, MDN, Toolkit, etc.
• CSS Working Group Wiki