309611 2026-03-10 16:35:12 -0700 [Site Isolation] @prefers-color-scheme doesn't see color-scheme from parent frames and above 2026-05-04 13:31:24 -0700 1 1 1 Unclassified WebKit Layout and Rendering WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED https://bugs.webkit.org/show_bug.cgi?id=284973 https://bugs.webkit.org/show_bug.cgi?id=311766 https://bugs.webkit.org/show_bug.cgi?id=311812 https://bugs.webkit.org/show_bug.cgi?id=312191 https://github.com/web-platform-tests/wpt/pull/59497 InRadar P2 Normal --- 1 kiet.ho kiet.ho bfulgham clopez kiet.ho simon.fraser webkit-bug-importer zalan oldest_to_newest 2188893 0 478621 kiet.ho 2026-03-10 16:35:12 -0700 Created attachment 478621 Test case 1 See the test case. We have an <iframe> (iframe 1) with color-scheme: dark. The inside document has another <iframe> (iframe 2) without color-scheme. The innermost document has a box which its background-color depends on @prefers-color-scheme. The color-scheme from iframe 1 should propagate through iframe 2 into the innermost document, so prefers-color-scheme should match "dark". But in WebKit, it doesn't match to "dark". On Chrome 147.0.7719.3 (Official Build) dev (arm64) and Firefox 150.0a1 (2026-03-10) (aarch64), the box is dark blue, regardless of environment color scheme. In WebKit, the box is light blue instead. 2188894 1 webkit-bug-importer 2026-03-10 16:35:19 -0700 <rdar://problem/172229372> 2188897 2 kiet.ho 2026-03-10 16:38:16 -0700 To add, this is found when investigating bug 284973. 2200451 3 kiet.ho 2026-04-14 17:50:12 -0700 Pull request: https://github.com/WebKit/WebKit/pull/62786 2205081 4 kiet.ho 2026-04-27 13:43:17 -0700 Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/59497 2205398 5 ews-feeder 2026-04-28 10:35:23 -0700 Committed 312212@main (9e45d72ed9ea): <https://commits.webkit.org/312212@main> Reviewed commits have been landed. Closing PR #62786 and removing active labels. 2207342 6 kiet.ho 2026-05-04 13:31:24 -0700 *** Bug 311812 has been marked as a duplicate of this bug. *** 478621 2026-03-10 16:35:12 -0700 2026-03-10 16:35:12 -0700 Test case 1 prefers-color-scheme-nested-iframe.html text/html 488 kiet.ho PGlmcmFtZSBzdHlsZT1jb2xvci1zY2hlbWU6ZGFyayBzcmNkb2M9IgogIDxpZnJhbWUgc3JjZG9j PScKICAgIDxzdHlsZT4KICAgICAgYm9keSB7IAogICAgICAgIGZvbnQtZmFtaWx5OiBzeXN0ZW0t dWk7CiAgICAgIH0KICAgICAgZGl2IHsKICAgICAgICB3aWR0aDogMTAwcHg7CiAgICAgICAgaGVp Z2h0OiAxMDBweDsKICAgICAgfQogICAgICAKICAgICAgQG1lZGlhIChwcmVmZXJzLWNvbG9yLXNj aGVtZTogZGFyaykgewogICAgICAgIGRpdiB7IGJhY2tncm91bmQtY29sb3I6IGRhcmtibHVlOyB9 CiAgICAgIH0KCiAgICAgIEBtZWRpYSAocHJlZmVycy1jb2xvci1zY2hlbWU6IGxpZ2h0KSB7CiAg ICAgICAgZGl2IHsgYmFja2dyb3VuZC1jb2xvcjogbGlnaHRibHVlOyB9CiAgICAgIH0KICAgIDwv c3R5bGU+CiAgICA8aDI+SW0gYW4gaWZyYW1lIGluIGFuIGlmcmFtZSE8L2gyPgogICAgPGRpdj48 L2Rpdj4KICAnPjwvaWZyYW1lPgoiPjwvaWZyYW1lPgo=