280307 2024-09-24 17:27:46 -0700 Regression in Safari 18: all: revert-layer breaks due to style changes on parent elements 2024-12-03 08:51:38 -0800 1 1 1 Unclassified WebKit Layout and Rendering Safari 18 Unspecified Unspecified RESOLVED CONFIGURATION CHANGED https://bugs.webkit.org/show_bug.cgi?id=283942 InRadar P2 Normal --- 1 govett webkit-unassigned ahmad.saleem792 bfulgham koivisto simon.fraser webkit-bug-importer zalan oldest_to_newest 2062890 0 govett 2024-09-24 17:27:46 -0700 This is a very strange bug that started occurring in Safari 18 on both macOS and iOS. It appears to be related to cascade layers. See the reproduction here: https://codepen.io/devongovett/pen/gOJOVGo Hovering over the outer element causes the color of the text to change, and unexpectedly, the width of the inner element collapses to zero. This appears to be due to the `all: revert-layer` rule applied to the inner element, which should simply revert to the previous cascade layer. The width should not be affected by the color change on the parent element. This resulted in regressions to Adobe's component library, which relies on cascade layers. revert-layer is used to ensure external styles outside a layer do not apply. This worked correctly in previous versions of Safari, and works fine in Chrome and Firefox as well. 2063190 1 ahmad.saleem792 2024-09-25 16:45:19 -0700 @Devon - it seems that Safari Technology Preview 203 already matches with Chrome Canary 131 and Firefox Nightly 132 and does not collapse like Safari 18.1 Beta do. Can you test this as well on your end? 2063277 2 govett 2024-09-25 21:13:12 -0700 Thanks! Yes, I can verify that it is broken in both 18.0 (20619.1.26.31.6) and 18.1 in macOS 15.1 Developer Beta 5 (20619.2.3.1), but works in Safari Tech Preview 203 (20620.1.6). Any idea how much farther ahead tech preview is than 18.1? Any chance whatever fixed this could make it into the shipping version? 2064277 3 ap 2024-09-30 10:15:48 -0700 STP is not necessarily ahead of these Safari builds. This is an important data point, but it does not prove in itself that the issue is already fixed. 2064278 4 webkit-bug-importer 2024-09-30 10:16:00 -0700 <rdar://problem/136976934> 2066629 5 simon.fraser 2024-10-09 13:45:27 -0700 Could you convert https://codepen.io/devongovett/pen/gOJOVGo into a self-describing test? We can't tell if this is fixed. 2066631 6 govett 2024-10-09 13:52:50 -0700 Sure, I updated it to have more description. Let me know if you're still not sure. 2066644 7 simon.fraser 2024-10-09 14:22:37 -0700 The test passes in Safari Tech Preview 203, so I think this is fixed. 2078630 8 govett 2024-12-02 14:16:59 -0800 Looks like this reproduction is fixed in Safari 18.2 beta, but there is still another broken case. I reported that as a separate issue here: https://bugs.webkit.org/show_bug.cgi?id=283942