293845 2025-05-30 20:18:05 -0700 will-change: offset-position should create a stacking context 2025-09-09 16:58:45 -0700 1 1 1 Unclassified WebKit CSS WebKit Nightly Build Unspecified Unspecified NEW https://github.com/w3c/fxtf-drafts/issues/609 InRadar P2 Normal --- 1 ahmad.saleem792 webkit-unassigned koivisto ntim simon.fraser webkit-bug-importer oldest_to_newest 2120866 0 ahmad.saleem792 2025-05-30 20:18:05 -0700 Hi Team, While going through Blink's test cases for motion path, I noticed three failures but one was about following case: Test Case Name - position-will-change-establishes-stacking-context.html Test Case Link - https://jsfiddle.net/6xkwroL0/ ^ Fails in WebKit ToT (295637@main) and Firefox Nightly 141 (20250528092647) while passes in Chrome Canary 139.0.7210.0 (Official Build) canary (arm64) . This fixes in WebkIt: > Source/WebCore/rendering/style/WillChangeData.cpp in function 'propertyCreatesStackingContext', add below: case CSSPropertyOffsetPosition: This progresses above Blink test case. Web Specification - https://drafts.fxtf.org/motion-1/#offset-position-property Just raising here to see whether we need to fix or we should as Blink to match WebKit and Firefox. Thanks1 2121465 1 gsnedders 2025-06-03 12:57:58 -0700 If we believe there's any web compat impact, we should raise a spec bug. If we don't, we could at least write a WPT test that it _doesn't_ establish a stacking context so there's some failing test, and/or file a bug against Chromium. 2122308 2 webkit-bug-importer 2025-06-06 20:19:14 -0700 <rdar://problem/152753709>