Hi Philip,
Thanks for reviewing. All the failing tests are understood. Here’s a
breakdown of the issues:
- Insets ink overflow tests (6):
- grid-gap-decorations-091.html, grid-gap-decorations-092.html,
flex-gap-decorations-066.html, flex-gap-decorations-067.html,
multicol-gap-decorations-038.html, multicol-gap-decorations-039.html
- The change was made last Friday, and the wpt runner is not running
the latest Chrome Canary version hence the reason why these are failing
- Minor fragmentation issues (3):
- flex-gap-decorations-fragmentation-005.html,
flex-gap-decorations-fragmentation-006.html,
multicol-gap-decorations-007.html
- These issues are well-understood, and we don't consider them
feature blocking, but we have work in progress to address them.
On Wednesday, April 29, 2026 at 2:36:19 AM UTC-7 Philip Jägenstedt wrote:
> Hey all,
>
> It's great to see this highly requested feature completed! The test suite
> <https://wpt.fyi/results/css/css-gaps?label=experimental&label=master&aligned>
>
> looks quite big in terms of number of tests, and tests across layout
> models, but there are 9 failing tests
> <https://wpt.fyi/results/css/css-gaps?label=master&label=experimental&aligned&q=chrome%3A%21ok%20chrome%3A%21pass>.
>
> Are the reasons for these failures understood? It it feasible to fix them
> all?
>
> Best regards,
> Philip
>
> On Tue, Apr 28, 2026 at 9:25 PM 'Sam Davis Omekara' via blink-dev <
> [email protected]> wrote:
>
>> *Contact emails*
>> [email protected], [email protected], [email protected],
>> [email protected]
>>
>> *Explainer*
>>
>> https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/main/CSSGapDecorations/explainer.md
>>
>> *Specification*
>> https://drafts.csswg.org/css-gaps-1
>>
>> *Summary*
>> CSS Gap Decorations enables styling of gaps in container layouts like
>> Grid and Flexbox, similar to ‘column-rule’ in multicol layout. This feature
>> is highly requested by web authors who must use hacks to style the gaps in
>> Grid and Flexbox layouts today.
>>
>> *Blink component*
>> Blink>Layout
>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ELayout%22>
>>
>> *Web Feature ID*
>> gap-decorations <https://webstatus.dev/features/gap-decorations>
>>
>> *Motivation*
>> Today, web authors rely on non-ergonomic workarounds such as the
>> following examples to apply styles to the gaps in Grid and Flexbox layouts:
>> https://www.smashingmagazine.com/2017/09/css-grid-gotchas-stumbling-blocks/#how-do-i-add-backgrounds-and-borders-to-grid-areas
>> https://x.com/geddski/status/1004731709764534274 CSS Gap Decorations
>> will allow authors to avoid such workarounds and apply styles in a seamless
>> manner provided by the platform.
>>
>> *Initial public proposal*
>> https://github.com/w3c/csswg-drafts/issues/10393
>>
>> *Search tags*
>> grid <https://chromestatus.com/features#tags:grid>, flexbox
>> <https://chromestatus.com/features#tags:flexbox>, multicol
>> <https://chromestatus.com/features#tags:multicol>, column
>> <https://chromestatus.com/features#tags:column>, row
>> <https://chromestatus.com/features#tags:row>, gap
>> <https://chromestatus.com/features#tags:gap>, decoration
>> <https://chromestatus.com/features#tags:decoration>
>>
>> *TAG review*
>> https://github.com/w3ctag/design-reviews/issues/1035
>>
>> *TAG review status*
>> Issues addressed
>>
>>
>> *Risks*
>>
>>
>> *Interoperability and Compatibility*
>> Gap Decorations is a highly requested feature among web developers. Early
>> discussions within the CSSWG meeting did not highlight any major concerns
>> from other browser vendors so far. See discussions on:
>> https://github.com/w3c/csswg-drafts/issues/10393
>>
>> *Gecko*: Positive (
>> https://github.com/mozilla/standards-positions/issues/1158)
>>
>> *WebKit*: No signal (
>> https://github.com/WebKit/standards-positions/issues/444)
>>
>> *Web developers*: Positive Developers are excited about the CSS Gap
>> Decoration feature. See discussions around this here:
>> https://github.com/w3c/csswg-drafts/issues/10393
>>
>> This also surfaced as a most requested missing feature in State of CSS
>> 2023. https://2023.stateofcss.com/en-US/usage/#css_missing_features
>>
>> The chromium tracking issue (https://issues.chromium.org/issues/357648037)
>> has 18 upvotes from developers.
>>
>> Following dev trials, the feature drew substantial enthusiasm across web
>> developer channels:
>>
>> Social media:
>> -
>> https://www.linkedin.com/pulse/day-164-new-way-style-gaps-emiliano-pisu-x0h1f
>>
>> - https://mastodon.social/@anatudor/114201225562770826
>> -
>> https://app.daily.dev/posts/a-new-way-to-style-gaps-in-css-9lolqu2yp
>> - https://x.com/Manz/status/1968682837453799570
>> - https://x.com/shadeed9/status/1822025452476592630
>> -
>> https://www.linkedin.com/posts/kirangrandhi_goodbye-to-css-hackshello-to-native-gap-activity-7341108234121900034-_ObL
>>
>>
>> Articles and videos:
>> - https://www.alwaystwisted.com/articles/styling-the-gap-with-css
>>
>> - https://youtu.be/L1-7dFQFb1c
>> - https://css-tricks.com/the-gap-strikes-back-now-stylable/
>> - https://heydesigner.com/newsletter/product-design-2025/
>>
>> *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?*
>> There are no WebView application risks.
>>
>>
>> *Debuggability*
>> DevTools already provides a layout overlay for gaps in Grid and
>> Flexboxes. Computed values for new properties introduced for gap decoration
>> will be exposed.
>>
>> *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-gaps
>>
>> *Flag name on about://flags*
>> enable-experimental-web-platform-features
>>
>> *Finch feature name*
>> CSSGapDecoration
>>
>> *Rollout plan*
>> Will ship enabled for all users
>>
>> *Requires code in //chrome?*
>> False
>>
>> *Tracking bug*
>> https://issues.chromium.org/issues/357648037
>>
>> *Estimated milestones*
>> Shipping on desktop
>> 149
>> DevTrial on desktop
>> 139
>> Shipping on Android
>> 149
>> Shipping on WebView
>> 149
>>
>>
>> *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).*
>> There are no open issues affecting the current level of the spec. All
>> open issues are scoped to a future level of the spec and do not introduce
>> web compat or interop risk for what is shipping now.
>>
>> *Link to entry on the Chrome Platform Status*
>> https://chromestatus.com/feature/5157805733183488?gate=6254826279927808
>>
>> *Links to previous Intent discussions*
>> Intent to Prototype:
>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/PH8PR00MB1471DB453B0D0025F83B1F06D8BA2%40PH8PR00MB1471.namprd00.prod.outlook.com
>> Ready for Trial:
>> https://groups.google.com/a/chromium.org/g/blink-dev/c/vmO3X2aYL2Y/m/f9LLE_W8AAAJ
>>
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>>
>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CH3PR00MB2681301B231C1C1B50B21206D8372%40CH3PR00MB2681.namprd00.prod.outlook.com?utm_medium=email&utm_source=footer>
>> .
>>
>
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