You know, I tried modding it, and I didn't get very far. You're definitely more skilled at this than I, Agathorn.
I'm looking forward to some of your future releases and mods of this theme. I'm going to keep chipping away at it on my own (what I'm ultimately trying to do is eliminate all the thick, blocky borders and have the entire interface be real slick and unobtrusive, like
Milquetowst's chat window, but grey). Who knows, maybe after a few weeks of banging my head against the wall trying to figure this out, I'll come up with something resembling useful.
In the mean time, keep up the awesome work -- I'm sure I'll be using your own UI & mods for a long time before I even figure out how to make my own.

And, really... thank you very much for updating this UI!
Anyways, as for bug-hunting, here's a couple:
1.
The exp. bar doesn't play nice with smaller fonts, apparently
2.
The frame on the persona window still displays some of the original UI.
3. Also with the persona window (and possibly others, although the inventory works fine), if you select "frame only" in the window options, it takes out the title bar, but the frame still extends to the top of where the title bar was, so you wind up with a goofy looking gap.