This has been, is, and always will be my favorite Fx theme. My sincere thanks to the dev for what was certainly a Herculean task in getting it to work with the interface whose name we do not mention. :-0
Contrary to what the previous reviewer reported, v. 5.7.0 has not caused any problems whatsoever for me on the ESP 24.6.0esrpre Nightly (Yes, I know 24.6.0 has been released), which I've been using for about five months. It works without a hitch two of my Win 7x64 machines and on three older XP machines.
In fact the only problem I had was with v. 33 Nightly - with the hated Aus .... interface.
The problem was that "Tools-Options" opens in a tab rather than a pop-up window, and this part of the interface was broken.
I saw the nice vertical row of red cats along the left, but nothing could be clicked. The only way to use Options was to temporarily disable Red Cats.
Fortunately, one of the kind contributors to the Fx Forums told me to me to change the pref "browser.preferences.inContent" to false. This was the solution!
Now everything's fine.