Siamak Mokhtari's Panda is a pretty fun and colorful light-on-dark theme.
He went to the trouble of making it work with CodeMirror so we did all the tweaks and stuff we needed to do to get it working on CodePen.
You'll find it in our split theme choice area in your Settings:
Select it and save and you'll be all Panda'd up:
We also already offered (one of the variations of) DuoTone Dark, so balancing out those columns is (one of the variations of) DuoTone Light by simurai.
Select it and you'll be in light land!