Web-Facing Change PSA: The '&' pseudo-class behaves as :where(:scope) in @scope rules
Anders Hartvoll Ruud
Contact emails
Specification
None
However, PR: https://github.com/w3c/csswg-drafts/pull/12914
Summary
The '&' pseudo-class now behaves like :where(:scope) (i.e. refers to the scoping root), rather than referring to the <scope-start> selector.
Miriam Suzanne wrote a blog post explaining about this change: https://css.oddbird.net/scope/parent-selector/
Blink component
Web Feature ID
Missing feature
Risks
Interoperability and Compatibility
This is theoretically a breaking change, and while @scope isn't widely used yet, I added a use-counter for this which recently hit stable: https://chromestatus.com/metrics/feature/timeline/popularity/5629 (~0.00016%)
Note: The use-counter triggers whenever '&' is seen in @scope at all. It does not mean that this change will actually cause an observable difference in the result for all of those 0.00016%.
The possibly breaking cases would be:
A) Here, the ‘&’ rule wins today, but will now lose against :where(:scope) due the change in specificity.
@scope (.foo) {
& { color: green; } /* Used to win; now loses. */
:where(:scope) { color: red; }
}
B) Since ‘&’ now refers to a specific element rather than a selector, selectors like the following can not match (since an element can not be its own sibling), whereas they previously could match:
@scope (.foo) {
& + & { color: green; } /* Cannot match anything anymore. */
}
Gecko: Positive (https://github.com/web-platform-tests/wpt/pull/53831) Mozilla initiated the WPT change. (And the spec change.)
WebKit: Shipped/Shipping (https://github.com/WebKit/WebKit/commit/4d5ebef83e17f6201e006f379de304fac6d196b4)
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?
None
Debuggability
No change.
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?
Yes
scope-invalidation.html
scope-name-defining-rules.html
Flag name on about://flags
Finch feature name
CSSScopeifiedParentPseudoClass
Rollout plan
Will ship enabled for all users
Tracking bug
https://issues.chromium.org/issues/445949406
Estimated milestones
M143
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5736934890668032?gate=6189707524440064
Note: This is a “Web-Facing Change” due to the API being changed in a trivial way with very low risk of breakage.
This intent message was generated by Chrome Platform Status.
Mike Taylor
On 10/8/25 6:28 a.m., Anders Hartvoll Ruud wrote:
Contact emails
Specification
None
However, PR: https://github.com/w3c/csswg-drafts/pull/12914
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