Editing CSS in a theme

I bought a theme called Photopia, and as usual, they refuse to answer emails for support on it. So, does anyone know of a method of visually seeing which elements are which on the page?

I’d like to delete some gaps, change some fonts, and add a border. Not a massive amount of work, but if you don’t know CSS then you have no idea of what you’re looking for. And lest face it, we buy themes because we don’t know CSS.

So, is there any app, program, plugin, or spell I can cast to enable me to see wysiwyg, or visually, the layout of the page so I can see what to alter?