Content Background

http://atily.info/product-category/free-stuff/

See that page at the bottom of the product grid there is the white background. I’ve done some css edits to make it show a different content background color to match the sidebar which works. But that’s only for the content. If there is any other space then it shows a white background.

Please could someone point out a good css to add to be able to keep the content the same background color whether there is content or not? Considering the sidebar is longer than the content.