Styling extension to work with different themes

[ez76]

I'm trying to build an extension that will look decent on different themes. I don't want to hardcode the colors, because if I make everything on a blue theme, it would look horrible on a red theme. I tried adding classes from the theme (vbmenu_control, for example) to my elements in order to bring in the colors, but it also brought in a bunch of other style rules that I then had to reset to default. Is there a standard practice for me? Or can someone point me to an extension that has taken a stab at this problem?

I've searched around the forums and haven't seen any posts relating to this, but I can't imagine that I'm the only one running into this. Any help is appreciated!

Thanks!