Bug 299995

Summary: Add align-self/justify-self dialog behavior to enable UA style for popovers
Product: WebKit Reporter: fantasai <fantasai.bugs>
Component: CSSAssignee: fantasai <fantasai.bugs>
Status: RESOLVED FIXED    
Severity: Normal CC: bfulgham, kiet.ho, koivisto, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: WebKit Local Build   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 299630, 300817    

fantasai
Reported 2025-10-01 17:25:16 PDT
The CSS Working Group recently added a new `dialog` value for align-self/justify-self in order to represent a better default behavior for popovers: centering by default, but using the position-area defaults when anchor-positioned. See https://github.com/w3c/csswg-drafts/issues/10258 This is an issue which trips people up a lot when using anchor positioning combined with popovers, see https://github.com/w3c/csswg-drafts/issues/12466 Opening this bug to track implementation of the new CSS behavior, which is required to update the UA stylesheet per https://github.com/whatwg/html/pull/11656
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Radar WebKit Bug Importer
Comment 1 2025-10-01 17:25:22 PDT
<rdar://problem/161779751>
fantasai
Comment 2 2025-10-01 17:30:49 PDT
Pull request: https://github.com/WebKit/WebKit/pull/51658
EWS
Comment 3 2025-10-02 01:30:34 PDT
Committed 300865@main (d7f2e52c03a8): <https://commits.webkit.org/300865@main> Reviewed commits have been landed. Closing PR #51658 and removing active labels.
fantasai
Comment 4 2025-10-15 10:28:22 PDT
Due to Web-compat, the CSSWG had to change tactics on solving this problem, see https://github.com/w3c/csswg-drafts/issues/10258#issuecomment-3407215102 Consequently, the `dialog` value has been removed from the specs.
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