Questions answered by this recipe
A skin with multiple semi-transparent layers over a static background. The background and the layer PNG are easily replaced. (For the layer graphic try Overlay, 20-50% opaque).
This skin has been tested and verified under Firefox 2, Safari, and Opera (PmWiki 2.2.0b16). I have no idea if it displays correctly under IE.
Surprisingly (not) IE does not handle this skin that great. IE6 fails the prerequisites for this skin so no surprises there. IE7 fares a little better but doesn't like all the layers.
Don't get me wrong this is a cool skin, but if you have people who are happy with their 'standard' browser it might not be for you.
Might have a look at IE7 rendering if I have some time.