Css for content_top and content_bottom

Hi,

This is a great theme and I'm very eager to use it. I've noticed though that when I use content_top and content_bottom block areas, that often (especially when the data in the block is large), the blocks stay the same size. I've played about with the css, but can't seem to change this problem. Hints of where to look to edit/remove sizings would be gratefully received.
Thanks,
Ian