Targeting issues for Login Page customizations

Continuing the discussion from Account Creation/Invitation Acceptance - special configurations and themes?:

Creating a class for the invite page was an amazing fix and made my invite page look great. I had not thought about the login page as I tend to stay logged in. I can’t believe I missed something so basic, but is it possible to do that same thing to that page? Ideally the page should appear similar.

Thanks for all the previous help @awesomerobot!