We don't have documentation for the different classes we implement in different areas of the modules or component. Honestly, to debug that, we used the Chrome Developer Tools (Menu->Tools->Developer Tools). From there, you can inspect any element in your HTML and actually make changes to the styles/CSS for that page to see the results. It's an invaluable tool, and just about all moder browsers have some sort of Developer Tools you can use to do that.
If you need more info, let me know,
Alex