Bishop, I created a new fork of the default theme:
http://greenexresp.github.io/
I set this one as my Custom theme, published it.
It looks like this: (text is red)
https://i.imgur.com/X55D0PO.png
However, I noticed there's still no copy on the uto server, like with for example spahreps.
I.E.:
http://utopia-game.com/shared/static...b.io/theme.css exists
http://utopia-game.com/shared/static...b.io/theme.css does not exist.
So I don't think it'll work. (Even though navigating in browser to the test page at http://greenexresp.github.io/ works, so things seem fine from Github point of view)