Change Background Color of Widget Area

Hello! I am trying to create an "As Seen On" banner along the bottom of my website, and I started creating this using a widget in the Footer Bar area, but it is appearing with a gray background, and I really want the background to be white. A lot of the logo images that will be appearing in this area have white backgrounds so they look bad on the gray. I realize I could just cut them all out and make them transparent PNG files, but I think I'd really like this area to be set off in white anyway. How would you go about changing the background color in a widget area?

Or is there some other better way to go about this altogether?