Level 1 = not much experience, maybe added something someone gave you.
Level 2 = Learning how to add in some CSS, but only in a few small places on a site
Level 3 = Feels comfortable trying a little bit of css on your own, block edits, etc.
Level 4 = Confident you can usually find the solution with css for most sections/blocks
Level 5= CSS is your language! From pseudo classes, to media queries and more!
(not specific issues, more broad general things)
we are planning the next year an want to make sure we include these things!