RESOLVED FIXED 290128
[css-anchor-position-1] scrolling with anchor()/position-area positioned element is broken 
https://bugs.webkit.org/show_bug.cgi?id=290128
Summary [css-anchor-position-1] scrolling with anchor()/position-area positioned elem...
Kiet Ho
Reported 2025-03-20 14:48:31 PDT
Created attachment 474652 [details] Reproduction Google Chrome 136.0.7077.0 (Official Build) canary (arm64) WebKit 292377@main See attached repro. Repro explanation: * Containing block is 300x500px and vertically scrollable * Green box is the anchor, orange boxes are positioned relative to the anchor using anchor() or position-area * Containing block contains a very long div to force scrolling * JS programmatically scrolls the containing block down by 100px The orange boxes should stay positioned to the green box, but this is not the case in WebKit. Note: this might be covered in some WPT scrolling tests.
Attachments
Reproduction (1.34 KB, text/html)
2025-03-20 14:48 PDT, Kiet Ho 		no flags
Details
Screenshot (Chrome on left, WebKit on right) (198.33 KB, image/png)
2025-03-20 14:50 PDT, Kiet Ho 		no flags
Details
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Radar WebKit Bug Importer
Comment 1 2025-03-20 14:48:38 PDT
<rdar://problem/147528893>
Kiet Ho
Comment 2 2025-03-20 14:50:43 PDT
Created attachment 474653 [details] Screenshot (Chrome on left, WebKit on right)
fantasai
Comment 3 2025-05-19 09:42:58 PDT
The behavior seems like we're double-applying the scrolling offset for these boxes.
fantasai
Comment 4 2025-05-19 09:43:55 PDT
My guess is that we're applying the magic scroll offset, but we shouldn't because these are in the same scroll container as their anchor.
fantasai
Comment 5 2025-05-23 15:45:45 PDT
Pull request: https://github.com/WebKit/WebKit/pull/45862
EWS
Comment 6 2025-05-26 11:01:04 PDT
Committed 295422@main (6a980b2b4039): <https://commits.webkit.org/295422@main> Reviewed commits have been landed. Closing PR #45862 and removing active labels.
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