I'm trying to give my H3's a background color that I want spanned the entire width of the column it's in and so far it is almost there expect there is a space from in the right side of each column.

My example: http://www.rcnitrotalk.com/news/ - notice "Search Site" and it's background color doesn't go all the way over and it's the same on the right column as well just not as bad, anyone know what I did wrong?