I need help with Twenty Twelve theme footer

Hi, all

Can anyone out there help me re-code Twenty Twelve so the footer is the full width of the page ( .site )? Not the width of the body (user’s viewport), just the theme’s page width?
It currently uses padding, and if I put a background color on the footer, it doesn’t go to the edge of the white background of the page (I have the body blue, and the page background white).

Thanks