Twenty Eleven Dropdown menu Colors

I notice that there is no edit in regular theme dashboard menus to change the color of the dropdown menus in Twenty Eleven. When the menus go beyond three pages, the menu runs over the main page and text… and because the background of the dropdown is white, it blends into my post and pages below. Is there a way to edit the background color of the drop down background?

I thought of changing my main pages to a light grey, but I want my pages to be readable. I guess I could also change my main pages to a very light, pale yellow. Any help would be appreciated as long as I am not going to have a major operation just to change a color.