interesting i see no place where you are defining a width at all other than the main page wrapper - try this one ... not sure if it will work....

#contentColumnMain
{width:100%;} at the very end of your css - let's see if it snaps it out.

Also, make sure you are doing a forced refresh when you look - i spent hours one nite trying to help someone on here and told them they fixed it over and over only to find out that the reason they didn't see it as "fixed" is cuz they weren't doing forced refresh