Bug 250059 – box-shadow does not paint correctly on inline elements

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Kevin Yank]

In Safari 16.2 on macOS 13.1, a display: inline element will fail to paint (or remove) a box-shadow correctly on hover/focus/active.

A work-around to force correct (re-)paints is to add a transparent outline of sufficient size to the same element(s).

Minimal demo: https://codepen.io/kevinyank/pen/rNrLEYa

HTML:
<p>In Safari 16.2 on macOS 13.1, a <code>display: inline</code> element (such as <a href="https://example.com/">this link</a>) will fail to paint (or remove) a <code>box-shadow</code> correctly on hover/focus/active unless an <code>outline</code> (even a transparent one) covering the same area is applied to the element too.</p>

<p>To reproduce, hover or tab over/out of the link and observe the incomplete repaints (particularly for the areas outside of the surrounding block). To force a full, correct paint, try zooming in/out (⌘+/-) with the link focused. Then tab away from the link to see part of the painted outline fail to be removed in the repaint.</p>

CSS:
a:is(:hover, :focus) {
  box-shadow: 0 0 0 5px red;
  outline: none;

  /* work-around: add a large enough transparent outline: */
  /*outline: 10px solid transparent;*/
}

/* Not necessary for the bug, but just to show that the painting is not cropping of overflow content. */
p,
a {
  overflow: visible;
}

[Radar WebKit Bug Importer]

<rdar://problem/103887993>

[alan]

Thanks for the bug report! This is still reproducible on trunk WebKit.

[alan]

Created attachment 464475 [details]
Patch

[alan]

Created attachment 464476 [details]
Screen recording with the patch applied

[alan]

Created attachment 464502 [details]
Patch

[EWS]

Committed 258923@main (003ff7e2ae82): <https://commits.webkit.org/258923@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 464502 [details].