Bug 271109 – [css-cascade] Hover specified only for an implicit scope does not work correctly

• Component: CSS
• Status: NEW

[Roman Komarov]

Created attachment 470397 [details]
Saved HTML of the CodePen test case

Steps to reproduce:

1. Open this test-case in Safari TP with the CSS Scoping flag on: https://codepen.io/kizu/pen/ZEZBLpK (or create an element with an implicit scope that contains `:hover` pseudo-class)
2. Hover over the first button.
3. Click on this button.

In Chrome's implementation of CSS scopes the hover works correctly, but in Safari it does not trigger on hover, but is triggered when clicking on the button — probably repaint does not happen when necessary.

This only happens when the `:hover` is applied _only_ as a part of the implicit scope, adding any other `:hover` for this button outside of it (regardless if it will be scoped) fixes the issue, so probably the `:hover` specified inside implicit scopes does not make the element subscribe to the state change?

[Karl Dubost]

Created attachment 470473 [details]
rendering in safari, firefox, chrome

Safari Technology Preview  190           19619.1.5.5.2
Firefox Nightly            125.0a1       12524.3.12
Google Chrome Canary       125.0.6371.0  6371.0

[Karl Dubost]

Safari Technology Preview  17.4          19619.1.5.5.2
Firefox Nightly            125.0a1       12524.3.12
Google Chrome Canary       125.0.6371.0  6371.0

[Radar WebKit Bug Importer]

<rdar://problem/125289425>