So all default headers(h1,h2,h3 etc. ) and titles tags can be set.If you are using any of those it should work automatically if not the class would come in handy
you can set the colors you want in a specific class.
I found out over the weekend that CSS files can't utilise variables within a module.
Which makes complete sense considering you wouldn't be able to have 2 of the same module with different colour referenced in a CSS file. Just doesn't make sense and I don't actuall know what I was thinking tbh