[Webkit-unassigned] [Bug 239418] New: Inconsistent CSS with position:absolute, animation on opacity and overflow:hidden

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=239418

            Bug ID: 239418
           Summary: Inconsistent CSS with position:absolute, animation on
                    opacity and overflow:hidden
           Product: WebKit
           Version: Safari 15
          Hardware: All
                OS: All
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Layout and Rendering
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: hubert.sablonniere at gmail.com
                CC: bfulgham at webkit.org, simon.fraser at apple.com,
                    zalan at apple.com

Created attachment 457747

  --> https://bugs.webkit.org/attachment.cgi?id=457747&action=review

reduction-test.html

We encoutered a inconsistent CSS behaviour between Chromium/Firefox vs. Webkit

The different behavior is observed when we combine an animation on the opacity with a position:absolute element (which is itself a child of an overflow:hidden element).

We tried to reduce our code to something really small to help the team figuring this out (see attachment).

We put different variations in this reduction test:

* animation:NO - overflow:hidden (same in Chromium/Firefox/Webkit)
* animation:NO - overflow:visible (same in Chromium/Firefox/Webkit)
* animation:YES - overflow:visible (same in Chromium/Firefox/Webkit)
* animation:YES - overflow:hidden (different in Chromium/Firefox vs. Webkit)

We observed the problem on:

* Safari on iPad 15.3/605.1.15
* Gnome Epiphany on Linux 42.1 (WebkitGTK 2.36.0)

We think it was working before (something like Safari 6 months ago) but it's not easy for us to test on older versions of Safari.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20220416/830af518/attachment.htm>