I made a .crx theme; specifically using transparent images (that's used for Clover tabs). Unfortunately, the only effect it had was making the transparent images dark. Im guessing there will be no transparency support in Clover until Google Chrome support transparency the same way Firefox does. Actually, this is one of the multiple reasons I use Firefox instead of Google Chrome.
I'm guess if Clover didn't break windows explorer textured backgrounds, I'd consider using it; despite the mis-matched non-transparent images used in Clover.