Change the sidebar background color in TypoXP theme?

If anybody uses the typoxp 2.0 theme, could you tell me how to change the background color of the sidebar?
I’ve looked through the css and I just can’t figure out what command is causing the sidebar to be grayish.
I’m knowledgable in css but not a guru, so perhaps there’s some fancy way of doing it.

I would try posting this question on the author’s blog, but it looks like they don’t respond to comments.
TIA