ExtendedToC header popup does not seem to show in firefox

[disberd]

The toc-header portion which shows the hide or save buttons for the whole ToC does not seem to show correctly in firefox.
The per-heading hide button instead do

[sprig]

Experiencing the same issue on safari 18.0.1

[sprig]

First observation; Manually changing the display of the top span inside the header of nav causes both the display/hide button as well as the save icons to display when hovering over the display/hide buttons /below/ (i.e. for the various TOC sections) but not when hovering over where those icons actually show:

EDIT:
Apparently I had something changed in the navbar while doing the previous tests. In a fresh session changing to display: flex causes only the show/hide icon to appear when hovering over the other ones.

[disberd]

I will try to look into this in the near future when I have some time.

While I can debug firefox I do not have/use mac or safari so troubleshooting that might be a bit more challenging

[sprig]

just because the bugs are so similar i guess that it currently works due to some unique behavior of chromium layout - the toc works fine for me on Edge and brave (and chrome). I noticed that when display is changed to container the icons show. However, the layout is messed up. Seems to be related to how each engine places out of bounds boxes.