Bug 301070 – [css-anchor-position-1] Anchor positioned popover temporarily misplaced during transition

• Status: NEW
• Component: Layout and Rendering

Hello,

On Safari 26, using a display discrete transition crashes the browser when used with anchor positioning. The issue can be reproduced here: https://codepen.io/bakura10/pen/GgoyVEB

Just click on One then Two to reproduce the issue.

No issue on Chrome.

[Alexey Proskuryakov]

Thank you for the report! I cannot reproduce this with Safari Technology Preview, but I also cannot reproduce this with an older build that I have around. Could you please attach a crash log, so that we could verify whether this is a known issue?

[alan]

I can make the browser hang on older build (e.g. 298280@main) but I am not seeing it on newer builds.

Hello,

On Safari 26 stable, the browser crashes. On TP, the browser does not crashes but the feature is not working correctly :).

[Alexey Proskuryakov]

Thank you for the clarification. It's not clear to me personally what "is not working correctly" means exactly, but perhaps layout experts CC'ed on the bug do understand.

Hello @Alexey,

Sorry, I just realized the Gist was incomplete on the TP. Please click on "Two" and click outside. You will see that the popover is repositioned incorrectly before being closed. On Chrome, the popover stays properly positioned during the whole animation.

[Alexey Proskuryakov]

Ah! Now I can reproduce. Re-titling to track the issue that we still need to fix.

[Radar WebKit Bug Importer]

<rdar://problem/163119386>

[Kiet Ho]

Might be dupe of https://bugs.webkit.org/show_bug.cgi?id=301057

[Kiet Ho]

I can't reproduce the crash, but the issue of anchor positioned popover at the wrong location when dismissing is a known issue that I'm working on. Part 1 of the fix is here: https://bugs.webkit.org/show_bug.cgi?id=301056

[Antoine Quint]

This seems specific to using an accelerated property, I filed bug 301461.

This crash instantly for me on Safari 26.