[Plugin: Gecka-submenu] Changing CSS Formatting and Spacing of Sub-Menu Items

I am sorry but I am a bit rusty, I am trying to set up sub-menus on a WordPress site for a friend. You noticed I set up a sample sub-menu for Books. However, the spacing is hideous. I was trying to read the PHP code for the required gecka-submenu plugin that makes this happen, and the generated HTML code to see the class directives. Is it getting it from my themes, or does the plugin do some on the fly modifications itself. I get confused since some of the elements have custom generated names, and I am not sure where to start.

Thanks for any help.