by Jim » Wed Apr 02, 2008 3:41 pm
I think that is set under Commerce Setup > Order System >Layout Info > Table Shade Color:
Note that this might change lots of things and not just the header background. There are a limited number of color fields that can be set in the back office of the store so some of them are used in multiple places in the templates. This make changing a specific color in only one place difficult to do.
If changing that changes too many places you would probably need to edit the various template include files and make the color changes there.