REGRESSION: Safari v14.1 computes element height to be 33,554,432 pixels

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[MarkG]

Created attachment 429138 [details]
screenshot of how jsfiddle looks in safari v14.1 vs how it should actually look

Safari v14.1 (build 16611.1.21.161.6) broke the display of one of our pages. I've replicated the problem here: https://jsfiddle.net/ao1xcs2q/ I have also attached a screenshot which shows how the jsfiddle renders on safari v14.1 (and iOS v14.5.1) and how it used to render on previous versions.

The element that breaks rendering is: <small class="noteshow">This could be a YouTube or Vimeo video, or something else</small>. The css rule that causes the problem is the margin-top: -10px. Safari v14.1 renders the element as 33,554,432 pixels high, completely obscuring any following content on the page. Disabling this rule makes makes the element render as expected.

[Alexey Proskuryakov]

I can reproduce with r277884.

[zalan]

Created attachment 429667 [details]
Test reduction

[Radar WebKit Bug Importer]

<rdar://problem/78471122>

[Radar WebKit Bug Importer]

<rdar://problem/78476119>

[zalan]

Created attachment 429707 [details]
Patch

[EWS]

Committed r278080 (238159@main): <https://commits.webkit.org/238159@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 429707 [details].