Add Background Color to Front Page Footer Widgets in Twenty Twelve

Hi,

I created a Twenty Twelve child theme. I’m trying to add a background color to all three widgets at the bottom of the home page but can’t figure out how to do this. I was able to add the background to the footer and to an area right above the widgets. Ideally the background would cover the entire widget area. Please view the site at https://corporate.triresources.com/

I used developer tools to troubleshoot this but still can’t find the correct element to use in my CSS.

Thanks for your help with this.