Unprefixed `stretch` keyword for size-declaring CSS properties

[BenjaminAster]

Description

The stretch value for (min-/max-)width/height/inline-size/block-size is currently implemented as -webkit-fill-available in Chromium and WebKit, and -moz-available in Firefox.

Note that there are some layout edge cases with floats etc. that still need to be fixed in various browsers, and the implementations generally differ significantly from the specification.

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This issue is one of seven issues regarding unprefixing CSS properties/values, originally all in #702 (as per https://github.com/web-platform-tests/interop/issues/702#issuecomment-2358173009). The aim is to group the properties together into multiple (but not seven) focus areas.

Specification

https://drafts.csswg.org/css-sizing-4/#sizing-values

Additional Signals

• Chromium bug
• WebKit bug
• Firefox bugs: 1, 2, 3.
• See also: o https://github.com/mozilla/standards-positions/issues/1054#issuecomment-2251104499 o https://github.com/web-platform-tests/interop/issues/702#issuecomment-2359032728

[yisibl]

Chrome is ready to improve it: https://groups.google.com/a/chromium.org/g/blink-dev/c/fxGpXGV0hYc

[davidsgrogan]

The first set of tests for this feature recently landed here.

There are a few more tests scattered around in other directories that we could probably also include if we just substitute stretch in place of the vendor prefixed version of stretch.

I also intend to land more tests for stretch behavior in the same directory during the week of Oct 28 - Nov 1.

[wpt-interop]

Thank you for proposing Unprefixed stretch keyword for size-declaring CSS properties for inclusion in Interop 2025.

We wanted to let you know that this proposal was not selected to be part of Interop this year.

On behalf of the entire Interop team, thank you for submitting this proposal for consideration. We got many more proposals than we could include in this year's project, necessitating some difficult choices. Please note this should not be taken as a comment on the technology as a whole, or our willingness to consider it for Interop in the future. We appreciate the work you put into your proposal, and would welcome your participation in future rounds of Interop.

For an overview of our process, see proposal selection. Thank you again for contributing to Interop 2025.

Posted on behalf of the Interop team.