:host(:has(...)) support

Description

This was proposed back in 2023 and 2025 by @Westbrook. It is currently implemented in both Firefox and Safari. Only Chromium browsers remain.

:host(:has()) selector combination, allows authors to select the host element if it has a descendent in the light DOM matching a provided relative selector list.

This would be extremely beneficial.

The implementation status in Chromium is currently marked as: Development work is on hold

Specification

W3C

web-feature

No response

Test Links

https://wpt.fyi/results/css/css-shadow?label=master&label=experimental&aligned&q=host-has

Additional Signals

https://github.com/web-platform-tests/interop/issues/791 (2025)
https://github.com/web-platform-tests/interop/issues/208 (2023)

https://drafts.csswg.org/css-shadow-1/#host-selector
https://drafts.csswg.org/selectors-4/#relational

https://issues.chromium.org/issues/40062355
https://github.com/w3c/csswg-drafts/issues/11859

Start with the linked WPT results for css/css-shadow and the host-has query, then read the CSS Shadow DOM and Selectors specifications. Review Chromium issue 40062355 and the linked CSSWG and Interop issues for current implementation status. Done means Chromium supports :host(:has(...)) and the relevant web-platform tests pass.