A user is seeing an odd empty overlay when focusing or hovering on interactive elements

[sandbergja]

Behavior

When @beth-german hovers over certain interactive elements (or focuses them with a tab key), an odd black or white box will cover up part of the screen. It is not consistent -- it will happen some times you hover over the hours menu item, but not others.

This happened on Firefox 127 and 129, on a Windows 10 machine (@beth-german 's machine, to be precise). Firefox had no extensions enabled.

• We could reproduce it in both dark mode and light mode, set at both the OS and browser level.
• We could reproduce it with both mouse hover and tab focus
• We could not reproduce on the same machine running Chrome, a Windows 11 machine with Firefox 129, or our MacOS laptops.

Impact of this bug

Unexpected behavior for one user. If it affects other users as well, it could be quite serious.

Implementation notes, if any

We need to find a better way to reproduce this issue before working on it.