Bug 263886

Summary:	Stacking order of absolutely positioned element affected by overflow
Product:	WebKit	Reporter:	Alexandre <alexandre>
Component:	Layout and Rendering	Assignee:	Nobody <webkit-unassigned>
Status:	RESOLVED CONFIGURATION CHANGED
Severity:	Normal	CC:	bfulgham, oliverjash, simon.fraser, zalan
Priority:	P2
Version:	Safari 17
Hardware:	Mac (Apple Silicon)
OS:	macOS 14
See Also:	https://bugs.webkit.org/show_bug.cgi?id=261302

Description Alexandre 2023-10-30 07:32:57 PDT

See: https://jsbin.com/yecanaguje/edit?html,output

Steps to reproduce:

1. Open the jsbin link in Safari 17
2. Change the horizontal window width until the stacking order changes.

Expected behaviours:

* `.foreground` should remain above `.background`

Notes:

* It doesn't seem to happen on Safari 16.
* `.foreground` remains over `.background` on other browsers
* Toggling overflow-x affect the stacking order of the element
* Creating a new stacking context seems to fix it (adding `isolation:isolate;` on `.container`)

Comment 1 Simon Fraser (smfr) 2023-10-30 10:29:22 PDT

Does this reproduce in Safari Tech Preview?

Comment 2 Simon Fraser (smfr) 2023-10-30 11:46:40 PDT

Very likely a dup of bug 261302.

Comment 3 Alexandre 2023-10-30 12:05:15 PDT

> Does this reproduce in Safari Tech Preview?

It seems fixed in Safari Tech Preview.

Comment 4 Alexey Proskuryakov 2023-10-30 13:53:17 PDT

Great news, thank you for checking!