I am curious if there is a good guide on what CSS styles are provided by default in Atom. I haven’t seen one yet, but it would be helpful.
You can actually bring up a styleguide within Atom that gives example classes for different UI elements and text styles. It can be found with the command palette or
You also have access to a number of less variables from the current theme in your packages’ stylesheets, which you can find listed in the source for the atom-dark-ui theme.