As of Firefox 107 I intend to turn contain-intrinsic-size and longhands on by default by default. It has been developed behind the 'layout.css.contain-intrinsic-size.enabled' preference.
More precisely, this will enable the 'contain-intrinsic-size' shorthand, the 'contain-intrinsic-width' and 'contain-intrinsic-height' longhands, and their logical equivalents 'contain-intrinsic-block-size' and 'contain-intrinsic-inline-size'.
Note the full grammar will be enabled, but 'auto' values only have observable effects when paired with the 'content-visibility' property, which is still being developed behind 'layout.css.content-visibility.enabled'.
Elevator pitch: https://developer.mozilla.org/en-US/docs/Web/CSS/contain-intrinsic-size#description
Platform coverage: all.
Status in other browsers:
- Blink: shipped the shorthand in version 83 (https://chromestatus.com/feature/5737051062272000),
the longhands in 95 (https://chromestatus.com/feature/5709654999957504),
and 'auto' values in 98 (https://chromestatus.com/feature/6740477866934272).
- WebKit: under development (https://github.com/WebKit/WebKit/pull/1799).
Meta bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1597529
Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=1792886
Standard: https://www.w3.org/TR/css-sizing-4/#intrinsic-size-override. It's a working draft, but it has been approved by CSSWG resolution (https://github.com/w3c/csswg-drafts/issues/4531) and passed TAG review (https://github.com/w3ctag/design-reviews/issues/437).
Standards Body: W3C CSSWG.
Mozilla's standards position: positive (https://github.com/mozilla/standards-positions/issues/512)
web-platform-tests: https://wpt.fyi/results/css/css-sizing/contain-intrinsic-size
This feature wasn't previously discussed in an "Intent to prototype" thread.