@vincentpolisi What issue are you having exactly? I just visited your site and checked from my iPhone, but I’m not seeing any issues as the background image is showing up as it should.
As I mentioned in my last comment, the background images aren’t necessarily supposed to resize 100% (only the inline images are), they’re only supposed to shrink a little bit due to the size of the image. It’s usually a large width and shorter height. The reason for this is so the images don’t look distorted by being resized unequally.