I'm looking for an overview of all the basic styling classes available within the default theme that can be reused everywhere. For example any special padding classes, button classes, etc.

Is there a list or any documentation available somewhere or do I have to dig through the stylesheets manually?

https://invisionpower.com/4guides/themes-and-customizations/css-framework/

 

Amazing, I was looking in the dev section and checking the standard guides completely slipped my mind, thank you @Meddysong.