Hi @mrcangrejero —
I’m the developer of the theme. I’m sure a list of CSS classes could be compiled but I don’t know how that would be better or more informative than looking at the style.css. I don’t have a list like that handy, so it would probably be a lot faster to look at the source.
I’m also unclear on what classes, exactly, you’re looking for. Obviously you aren’t referring to things that are editable via the customizer because those can just be changed in the theme customizer. Again, since I don’t know what, specifically, you are looking for, it’s probably easier to just look at the style.css and use your browser tools or Firebug to tell you the classes for the specific areas that you are wanting to make adjustments to.
Here is a link to the style.css on Github with the lines highlighted that directly affect, or are unique to the theme structure: https://github.com/jazzsequence/museum-core/blob/master/style.css#L175-L689