@lah7 Thanks for this really helpful information.
I had a look and there are instructions about how to check out and build chromium for linux and video tutorials too. That looks really daunting to me!
Still I wish some focus would be put on fixing this. I notice the Brave or Chrome Browser UI does not obey Linux themes but they should like Firefox does. In that case, as you say, Bookmark folders could be a colour that is much easier on the eyes.
Cheers,
Flex