Grid Display of Category Thumbnails in WP eStore

I'm using WP eStore and am having a little formatting difficulty. When I call for the thumbnails of the categories in the store, they are shown as a list (vertical) as in the following page.
http://normhamilton.ca/photography/f...-and-canvases/

I'd like to have them show as a grid. (horizontal across the page just like a photo gallery)
I'm thinking it has something to do with this CSS that I found, but I'm not sure. If I turn off the "both" when inspecting elements it causes a change, but not what I want.

.eStore-fancy-clear {
clear: both;
}

Any ideas?

Norm