I have noticed that in MacOS 26, the Safari browser takes on the color of the header in this forum. Can that be fixed? It only happens with this forum and the Blocs.app forum. Other uses of this forum software, (in my experience) do not display this quirk. Neither do other bChrome or Firefox, just my Safari.
This is a new feature of Safari when using the Liquid Glass UI. It looks like it takes the colour of the top row(s) of pixels of the site itself.
It happens with my own sites too, and some other sites I frequent.
You can switch it off in:
macOS > Settings > Appearance > Windows > Set window background color to match content (or something similar in your language)
Cheers,
Erwin