As said by the author of this awesome theme, a lot of love has been put into it, so that it looks great in any windows theme.  If you want to pick it up, you can grab it on the Firefox Add-ons site or visit the official hmmXP theme site to get the latest version.

No huge distractions here. It is simple, lightweight but still gives you that visual refresh you might be looking for when changing your Firefox theme around. The light blueish-purple is a welcome too as it is all very pleasing to the eye. Mix that with the hint of green and the theme – it is delicious. I would lick it if I could, but I have a feeling my monitor wouldn’t like that too much.