CSS for thumbnails

I’m using iimage gallery to add thumbnails to my posts but am lost when it comes to configuring the look and feel of it.
For instance, I’d like to add padding/space between the thumbnails where there isn’t any currently.
On my site, I’ve got a test post up with the current configuration. The bottom gallery is inside of a blockquote.
Is this something I can easily configure, per post, with simple html tags, or is it something I should configure with CSS?
Thanks very much.
http://ryanhealy.com