CSS / HTML Mystery Problem

Hi everyone. I am trying to customize a theme and running into a mystery problem that is beyond my abilities. If you visit the blog:

http://nashvillephotographersredefined.com/

You can see that right after the main content area starts (the slightly darker gray area below the big header image) I have inserted an image (#cont-head { background: url(images/cont-head.jpg) no-repeat; }) to round of the corners of the content area. You can likely see the problem, there is a tiny gap between that and the image and the main y-repeated content background. Anyone able to pinpoint why this is? Thanks for ANY help.