227615 2021-07-02 03:14:48 -0700 animation-fill-mode does not correctly apply viewport-based units 2026-03-26 15:14:32 -0700 1 1 1 Unclassified WebKit Animations WebKit Nightly Build All All RESOLVED FIXED https://github.com/web-platform-tests/wpt/pull/58793 https://will.harris.ch/tcr-animation-fill-mode.html HasReduction, InRadar P2 Normal --- 1 will-web-webkitbugs ahmad.saleem792 ahmad.saleem792 dino graouts koivisto smoley webkit-bug-importer oldest_to_newest 1774401 0 will-web-webkitbugs 2021-07-02 03:14:48 -0700 If an animation is applied with an "animation-fill-mode", and the values in the first/last animation frame are expressed using viewport units (vw, vh), the affected element will not be correctly positioned if the viewport is subsequently resized after the animation has ended (e.g. desktop browser when resizing, mobile browser when orientation is changed). The attached test case reduction shows the issue. It contains three divs, all positioned with viewport units: - one reference div, unanimated - one div animated without "animation-fill-mode" - one div animated with "animation-fill-mode" The animated divs share the same animation and CSS positioning. The only difference is that the last div's animation also uses a fill mode. When the browser window is resized, the top two divs move correctly, and remain aligned with a reference marker line. The last div does not move as expected to respect the changed viewport size. 1774402 1 will-web-webkitbugs 2021-07-02 03:16:16 -0700 Chrome and Firefox show what I would consider the correct behaviour. 1774403 2 webkit-bug-importer 2021-07-02 03:23:53 -0700 <rdar://problem/80075191> 1777312 3 smoley 2021-07-15 13:23:19 -0700 It looks like the test case failed to attach. Please try adding it again. 1777497 4 will-web-webkitbugs 2021-07-16 06:40:50 -0700 Sorry, test case added in the URL field: https://will.harris.ch/tcr-animation-fill-mode.html 1791458 5 graouts 2021-09-08 07:38:50 -0700 Thanks for filing this., I can reproduce the issue with STP 131. 2014400 6 ahmad.saleem792 2024-02-16 01:24:59 -0800 It is still reproducible in STP188 using attached test case where while animation is running, if you change window size, the last div is stuck. 2193429 7 ahmad.saleem792 2026-03-25 02:02:42 -0700 Pull request: https://github.com/WebKit/WebKit/pull/61312 2194030 8 ews-feeder 2026-03-26 11:46:39 -0700 Committed 310007@main (243e5fe708ed): <https://commits.webkit.org/310007@main> Reviewed commits have been landed. Closing PR #61312 and removing active labels. 2194082 9 ahmad.saleem792 2026-03-26 15:14:32 -0700 Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/58793