don't set colours with module stylesheet

It's generally a bad idea for modules to set colours in their CSS files. It only means site developers will have to reverse or override it to fit in with their site theme. I don't think the current colours even fit terribly well with the Garland default theme...

Modules should do as little as possible with CSS -- I'm not even sure that presenting the email as a bunch of positioned DIVs is the best way either, but that's another issue ;)