For Safari 14.0

If you have an earlier version of Safari, see https://github.com/xavi-dev/gmail-reverse-safari.git

There isn't a menu item for Show Extension Builder in Safari 14.0

I did my best with Xcode and the instructions from Apple and copied in the style.css file in to the Safari Extension Target, and I think it works(Develop-> Allow Unsigned Extensions, and then used Safari Preferences, tick/enable the extension). It may require re-enabling every time you restart Safari.

I didn't do a social fork with modification because I am completely clueless about Apple development, and it looks completely different But if anyone wants to take a whack at it, this is what I have on my system.