I am customizing twenty ten with my own header image. I also changed the default header dimensions from 940 x 198, to 940 x 252. That is all fine. The problem is that my image has transparent space on the top left and top right. However, the color that transparency reveals is not the color of the #wrapper as I had hoped. It is instead a much darker color.
I can't find anything in the stylesheet or in the php files to change this. Anybody know how? I've been looking for something like: header background-color, or something like that.