Bug 262968

Summary: Styles on elements of parents with :last-child pseudo-classes not being udpated
Product: WebKit Reporter: Ethan Wong <bunnnywong>
Component: CSSAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: ahmad.saleem792, bfulgham, koivisto, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: Safari 17   
Hardware: All   
OS: All   
Attachments:
Description Flags
A page that reproduces this issue
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Screen recording of this issue none

Description Ethan Wong 2023-10-10 11:13:51 PDT
Created attachment 468154 [details]
A page that reproduces this issue

Styles on elements of parents with :last-child pseudo-classes may not update correctly when new elements being added.

The attached html file reproduces this issue.
Comment 1 Ethan Wong 2023-10-10 11:14:35 PDT
Created attachment 468155 [details]
Screen recording of this issue
Comment 2 Radar WebKit Bug Importer 2023-10-10 13:52:37 PDT
<rdar://problem/116759051>
Comment 3 Ethan Wong 2023-10-14 04:17:31 PDT
Pull request: https://github.com/WebKit/WebKit/pull/19082
Comment 4 Ahmad Saleem 2023-12-17 10:13:12 PST
@Ethan - I noticed you have closed your PR but while testing the reduction / test case on WebKit ToT (272190@main), it is still reproducible.