help with annoying white background... curvycorners issue?

The website: http://mars1.nimbit.com/

Okay, so I recently just swapped out the white container images with a transparent version of it so it would be easier to switch out the gradient background and it seems that no matter what I do, I can't make the corners transparent. I set the top image transparent and the bottom to gray so it's easier to see what's going on.

I have deduced that it's a corner with curvycorners, but I'm not familiar enough with Drupal (someone else installed it) and its containing stylesheets to understand why that would happen. Is it even a problem with the script? Can someone point me in the right direction? Any help would be greatly appreciated!