So, I'm trying to change the background color of the cart on the right hand side of the screen on this page:

I am new to using the firefox inspect tool. I found css on the page that is styling it, but can't find the style sheet that it is on

background: none repeat scroll 0% 0% rgb(36, 36, 36);

Is there a way using this tool to see what css file that this rule is in?