Bug 252999

Summary:	Unexpected result as paragraph z-index changes depending on CSS scale
Product:	WebKit	Reporter:	Adam Gamble <adam.gamble>
Component:	Compositing	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	simon.fraser, webkit-bug-importer, zalan
Priority:	P2	Keywords:	InRadar
Version:	Safari 16
Hardware:	Unspecified
OS:	Unspecified

Description Adam Gamble 2023-02-27 09:26:30 PST

Example case: https://jsfiddle.net/mdfs3tb0/

An outer div scales a fixed-size inner div (a 'canvas') which contains some elements positioned with translate().

Scaling past the bounds of the inner div will cause the z-index of the stacking order of the paragraph element to change.

This doesn't seem to happen in other browsers and seems unexpected.

Comment 1 Simon Fraser (smfr) 2023-02-28 12:38:27 PST

I think this is about clipping and the overlap map; I recall another bug that's probably related.

Comment 2 Radar WebKit Bug Importer 2023-03-06 09:27:15 PST

<rdar://problem/106292875>