I am really new to CodeCademy and I have a great experience here. I just wanted to share a little project of making dark mode version of CodeCademy (since I am a night-owl, too). I just think it would be helpful if I share here, too. I am looking forward for ideas and suggestions from you to improve it (including report of broken elements). For now the code is really messy, but I think it does the work (for now).
It would be a really great (I think) if there is official dark mode from CodeCademy.
But for you who really want it: https://userstyles.org/styles/181606