Hi Vanessa, which theme is that? You should be able to find the theme name on the Add-ons page (Ctrl+Shift+A), Themes section. If the name sounds common, please mention the author (this is listed after you click the theme name).

IT's the galaxy space theme. The side bar bookmark is the only one that is grayed out and is not on the same theme.

I can't figure out which one it is, so I'm having trouble testing. I probably tried 10 and didn't see an exact match. Do you see it here:

https://addons.mozilla.org/en-US/firefox/search/?q=galaxy%20space&type=statictheme

Of those, I think "Space Galaxy ANIMATED stars" looked good, but maybe a bit distracting.

It's Galaxy Space Theme, I noticed that it has not been updated since 2023. I guess it does not automatically update.