the only major changes as far as classes go is related to icons and buttons which are there own modules so very easy to decipher
also don't dive into the html before using dev tools in your browser.
One of the improvements that I have been working on is separating the js from the html and css meaning less hidden rendering so that more can be viewed and accomplished via dev-tools interface making it easier to fix/tweak the themes. The only outlier that still remains is the shity way prosilver accomplishes responsiveness with JS instead of pure css.
in that regard a lot of the responsiveness has been re-accomplished via the responsive.css file. Most of the responsivity is found in this file.