Spacing of home page images with Imbalance theme

Hi
This i am sure is something pretty simple but for the life of me i cannot figure out how to get it sorted..

If you look at my site, http://www.simonwestmore.com, on the home page i am trying to get some space between the images to each of the galleries but no matter where i try make a change in the style.css file i cannot get some form of space between them..

It really is driving me mad now so if anyone can have a look and let me know where i need to make the change it would be greatly appreciated!