Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: d4ee79d749dda787d8229620428597029552a999
https://github.com/WebKit/WebKit/commit/d4ee79d749dda787d8229620428597029552a999
Author: Alan Baradlay <[email protected]>
Date: 2026-04-25 (Sat, 25 Apr 2026)
Changed paths:
A
LayoutTests/imported/w3c/web-platform-tests/css/css-flexbox/position-relative-percentage-top-005-expected.txt
A
LayoutTests/imported/w3c/web-platform-tests/css/css-flexbox/position-relative-percentage-top-005.html
M Source/WebCore/rendering/RenderBoxModelObject.cpp
Log Message:
-----------
REGRESSION (311908@main): Autoplay button in YouTube controls is misplaced
https://bugs.webkit.org/show_bug.cgi?id=313304
<rdar://175562243>
Reviewed by Simon Fraser.
312944@main added hasDefiniteHeightByStyle as a fast style-only check for
resolving percentage top/bottom on relatively positioned elements.
This fast path incorrectly returns 'no, the box has no ancestor with definite
height' for certain nested flex content.
Example:
<div class=outer style="display: flex; height: 200px">
<div class=middle style="display: flex; align-items: flex-end">
<div class=inner style="height: 100%">
<div style="position: relative; top: 100%">
The "inner" div is a flex item inside "middle" with alignment flex-end (not
stretch):
Old code returned false immediately: "flex container is not stretch, not
definite" <- incorrect.
However
1. "inner" has height: 100% which resolves against "middle"
2. "middle" is a flex item inside "outer" with alignment stretch (default)
3. stretch gives "middle" a definite cross size (200px from "outer")
The fix: when the cross-axis alignment is not stretch, don't return false - fall
through to the normal logicalHeight checks. The percentage/stretch/auto checks
below the flex-item block will walk the ancestor chain and find the definite
height through the normal resolution path.
*
LayoutTests/imported/w3c/web-platform-tests/css/css-flexbox/position-relative-percentage-top-005-expected.txt:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/css/css-flexbox/position-relative-percentage-top-005.html:
Added.
* Source/WebCore/rendering/RenderBoxModelObject.cpp:
(WebCore::hasDefiniteHeightByStyle):
Canonical link: https://commits.webkit.org/312020@main
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