Bug 294902

Summary: mada.com.sa: broken animation for "timeline" compared to Chrome
Product: WebKit Reporter: Antoine Quint <graouts>
Component: AnimationsAssignee: Nobody <webkit-unassigned>
Status: RESOLVED DUPLICATE    
Severity: Normal CC: graouts, koivisto, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Reduced test case none

Antoine Quint
Reported 2025-06-24 07:12:15 PDT
Steps to reproduce: 1. Go to - https://www.mada.com.sa 2. Scroll till you see timeline of 1993 — 2022 3. Notice the animation + scrollbar This should not cause the page to jump or it shouldn’t be this jumpy (page jump is more visible, if you are on end of page - footer area)
Attachments
Reduced test case (1.14 KB, text/html)
2025-06-24 07:18 PDT, Antoine Quint
no flags
Antoine Quint
Comment 1 2025-06-24 07:12:24 PDT
Antoine Quint
Comment 2 2025-06-24 07:18:01 PDT
Created attachment 475639 [details] Reduced test case The content can be reduced to something as simple as: ``` <style> h1 { margin-top: 0; animation: shrink 1s linear; } @keyframes shrink { from { font-size: 100px } } </style> <h1>Hello World!</h1> ``` Somehow the `margin-top` style seems to be ignored and the element top left corner moves as the `font-size` animates. This does not occur in Chrome and Firefox.
Antoine Quint
Comment 3 2025-06-24 07:24:35 PDT
Note that <h1> has the following style declared in the UA stylesheet: ``` h1 { display: block; font-size: 2em; margin-block-start: 0.67em; margin-block-end: 0.67em; margin-inline-start: 0px; font-weight: bold; } ``` It appears to me that there may be a cascade issue here and that the margin value used here is the `rem` value specified in the UA stylesheet instead of the `0` value set in the page's `h1` rule.
Antoine Quint
Comment 4 2025-06-24 07:44:19 PDT
Huh, this does not reproduce in STP 122!
Antoine Quint
Comment 5 2025-06-24 07:44:55 PDT
Sorry, meant to say it reproduces in STP 122 but not on a ToT build. So this appears to have been fixed recently, will find the exact change that fixed this.
Antoine Quint
Comment 6 2025-06-24 07:51:07 PDT
This progressed with 296304@main, the fix for bug 284527. *** This bug has been marked as a duplicate of bug 284527 ***
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