255736 2023-04-20 10:52:45 -0700 [margin-trim][block layout] self-collapsing children at block-end don't have nested content trimmed 2023-04-26 15:36:23 -0700 1 1 1 Unclassified WebKit Layout and Rendering WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED https://github.com/web-platform-tests/wpt/pull/39674 InRadar P2 Normal --- 253610 253454 1 sgill26 sgill26 bfulgham simon.fraser webkit-bug-importer zalan oldest_to_newest 1950117 0 sgill26 2023-04-20 10:52:45 -0700 If you have a block structure that is something similar to the following: <container> <item style="margin-bottom: 10px"></item> <item style="margin-bottom: 10px; height: 0px;"> <item style="margin-bottom: 10px; height: 0px;"> <item style="margin-bottom: 10px; height: 0px;"> <item style="margin-bottom: 10px; height: 0px;"></item> <item style="margin-bottom: 10px; height: 0px;"></item> </item> </item> </item> </container> We currently trim the last child, which is self collapsing, and its margins correctly, but none of the children nested within it are trimmed. Since these are at the block-end and we trim the margins that are collapsed through for the container, none of the inner margins end up participating in margin collapsing with the container's margin and renderings look correct. However, with the tests added as a part of 253610 we can actually see that these margins are not trimmed by looking at the computed style values. 1950118 1 webkit-bug-importer 2023-04-20 10:53:51 -0700 <rdar://problem/108327029> 1950121 2 sgill26 2023-04-20 11:10:57 -0700 Pull request: https://github.com/WebKit/WebKit/pull/12982 1950937 3 sgill26 2023-04-24 20:52:48 -0700 Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/39674 1951459 4 ews-feeder 2023-04-26 15:36:20 -0700 Committed 263439@main (809b95bb1a78): <https://commits.webkit.org/263439@main> Reviewed commits have been landed. Closing PR #12982 and removing active labels.