LGTM2 (Adoption now added)
/Daniel
On 2026-10-28 06:24, Chris Harrelson wrote:
Actually I take that back - I'll add my LGTM once the Adoption gate is
filled out in the Chromestatus entry.
On Wed, Oct 28, 2026 at 5:23 AM Chris Harrelson
<[email protected]> wrote:
LGTM2
On Tue, Oct 27, 2026 at 7:08 PM Alex Russell
<[email protected]> wrote:
LGTM1; thanks for the note about interop risk, makes this
easier to approve.
On Monday, October 26, 2026 at 2:56:32 PM UTC-7 Chromestatus
wrote:
*Contact emails*
[email protected]
*Specification*
https://drafts.csswg.org/css-values-4/#linked-properties
*Summary*
Makes the computed value of the background-* longhands
keep the number of comma-separated values the author
specified, instead of repeating or truncating it to the
background-image layer count. Repeating and truncating are
used-value behavior: "The computed values of the
coordinating list properties are not affected by such
truncation or repetition." This feature would implement
the behavior defined in the
https://drafts.csswg.org/css-values-4/ Appendix A.
*Blink component*
Blink>CSS
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ECSS%22>
*Web Feature ID*
background <https://webstatus.dev/features/background>
*Motivation*
The behavior defined in the "Appendix A: Coordinating
List-Valued Properties" of the CSS Values And Units L4
specification has been discussed recently and agreed that
it should stand. This makes Chrome the only browser
diverging in the specified behavior.
*Initial public proposal*
/No information provided/
*TAG review*
/No information provided/
*TAG review status*
Not applicable
*Goals for experimentation*
None
*Risks*
*Interoperability and Compatibility*
The new behavior this feature provides is implemented
already by Firefox and Safari, so it's Chrome catching up
in this case; hence, the interop risk is zero. Regarding
compatibility, making the background-* properties align
"coordinated list group" is what matches the current
specified behavior, which the CSSWG agreed on keep. Some
engines implemented weird truncation rules, that's why
there were some WPT not following the spec. The resolution
[1] was to update the tests and observe whether any compat
issue appears in the next months. [1]
https://github.com/w3c/csswg-drafts/issues/12791#issuecomment-4040285092
/Gecko/: Shipped/Shipping Firefox was the only one
implementing the behavior defined in the spec.
https://github.com/w3c/csswg-drafts/issues/12791#issuecomment-4040285092
/WebKit/:
Shipped/Shipping
(https://developer.apple.com/documentation/safari-technology-preview-release-notes/stp-release-246)
See
the bug https://bugs.webkit.org/show_bug.cgi?id=315771 for
details
/Web developers/: No signals
/Other signals/:
*WebView application risks*
Does this intent deprecate or change behavior of existing
APIs, such that it has potentially high risk for Android
WebView-based applications?
/No information provided/
*Debuggability*
/No information provided/
*Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, ChromeOS, Android, and Android
WebView)?*
Yes
*Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?*
Yes
*
https://wpt.fyi/results/css/css-backgrounds/parsing?label=experimental&label=master&aligned
<https://wpt.fyi/results/css/css-backgrounds/parsing?label=experimental&label=master&aligned>
*
https://wpt.fyi/results/css/css-backgrounds/animations/background-position-interpolation.html?label=experimental&label=master&aligned
<https://wpt.fyi/results/css/css-backgrounds/animations/background-position-interpolation.html?label=experimental&label=master&aligned>
*
https://wpt.fyi/results/css/css-backgrounds/animations/background-size-interpolation.html?label=experimental&label=master&aligned
<https://wpt.fyi/results/css/css-backgrounds/animations/background-size-interpolation.html?label=experimental&label=master&aligned>
*
https://wpt.fyi/results/css/css-masking/parsing?label=experimental&label=master&aligned
<https://wpt.fyi/results/css/css-masking/parsing?label=experimental&label=master&aligned>
*Flag name on about://flags*
/No information provided/
*Finch feature name*
/No information provided/
*Non-finch justification*
/No information provided/
*Rollout plan*
Will ship enabled for all users
*Requires code in //chrome?*
False
*Tracking bug*
https://issues.chromium.org/issues/40855581
*Estimated milestones*
Shipping on desktop 159
Shipping on Android 159
Shipping on WebView 159
Shipping on iOS 159
*Anticipated spec changes*
Open questions about a feature may be a source of future
web compat or interop issues. Please list open issues
(e.g. links to known github issues in the project for the
feature specification) whose resolution may introduce web
compat/interop risk (e.g., changing to naming or structure
of the API in a non-backward-compatible way).
/No information provided/
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5144333908049920?gate=6114123363516416
*Links to previous Intent discussions*
Intent to Prototype:
https://groups.google.com/a/chromium.org/g/blink-dev/c/eny3Exk0b8w/m/HiXscXadAgAJ
This intent message was generated by Chrome Platform
Status <https://chromestatus.com>.
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