So are we not able to change themes now?
I disabled that along the way. We had enabled it at first, then, I think, disabled it, then I don't know what became of it.
Since, it seems, at least one person wants an alternate theme, I'll re-enable it. Consider other themes "unsupported", however; if something doesn't work, I won't fix it, and if we add something, you won't see it.
Ultimately, we may wind up with a unified look, across the sites. At that point, we'd get rid of the option again, and you'd be forced to look at our wonderfully lucrative advertisements. So, enjoy it while it lasts.