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What’s next for CSS?

CSS Database is a comprehensive list of CSS features and their positions in the process of becoming implemented web standards.

What are the stages?
Feature Stage Description Specification Polyfills
@apply rules Rejected A syntax for storing properties in a named variable, referenceable in other style rules http://tabatkins.github.io/specs/css-apply-rule/
aspect ratio Stage 0 A spec for an Aspect Ratio property for CSS https://tomhodgins.github.io/aspect-ratio-spec/aspect-ratio.html
color expressions Stage 2 A function used to modify a color https://drafts.csswg.org/css-color/#modifying-colors
custom media queries Stage 2 An at-rule used to define aliases representing media queries https://www.w3.org/TR/2016/WD-mediaqueries-4-20160126/#custom-mq
custom selectors Stage 2 An at-rule used to define aliases representing selectors https://drafts.csswg.org/css-extensions/#custom-selectors
element queries Stage 0 A spec for a container-style element query syntax https://tomhodgins.github.io/element-queries-spec/element-queries.html
gray expressions Stage 2 An expression used to specify fully desaturated colors https://drafts.csswg.org/css-color/#grays
grid layout Stage 4 A syntax for using a grid concept to lay out content https://www.w3.org/TR/css-grid-1/
hex alpha colors Stage 2 A 4 & 8 character hex notation for color to include the opacity level https://drafts.csswg.org/css-color/#hex-notation
hwb() expressions Stage 2 An expression used to specify colors, similar to HSL, but often even easier for humans to work with https://drafts.csswg.org/css-color/#the-hwb-notation
:matches pseudo-class Stage 3 A pseudo-class used to match a selector list https://drafts.csswg.org/selectors-4/#matches
media() expressions Stage 0 An expression used to define media queries within values https://jonathantneal.github.io/media-expressions-spec/
nesting rules Stage 1 A syntax for nesting relative rules inside another http://tabatkins.github.io/specs/css-nesting/
:not list pseudo-class Stage 3 A pseudo-class used to ignore a selector list https://drafts.csswg.org/selectors-4/#negation
range media queries Stage 3 A syntax for defining media query ranges using ordinary mathematical comparison operators https://drafts.csswg.org/mediaqueries/#mq-ranges
variables Stage 5 A syntax for defining custom values accepted by all CSS properties https://www.w3.org/TR/css-variables/