Hi, I recently made a dark theme for TOKI's coding platform, TLX.
I did not simply use a color inverter for better results.
You can find it at my GitHub repo (along with the installation instruction). The script is new so there might be some bugs. Feel free to report a bug or giving any suggestions by opening an issue at the repo :))
Update 21/09/2020: Added copy button to copy the samples.
Update 07/10/20: You can use alt
+ arrow up
or arrow down
on your keyboard to move between contest menus (overview, announcement, problems, clarification, scoreboard, etc.)
Update 08/10/20: You can easily toggle between light and dark mode using the button at the top right corner of the screen.
Special thanks to sigma_g for guiding me. Check out his awesome dark theme for codeforces