Help Me with CSS for Firefox

hi, I need help with this css code for firefox, I'm not a programmer I tried to use AI but couldn't fix it. I would like someone to fix this css script for firefox to add the close minimize and full screen buttons, with my current css they don't work, can you help me, with these buttons I could completely switch to firefox.

link of the autor of the script: https://gist.github.com/morrolinux/87aa37396432ea5d14a9220bc4892100

link of the script: https://privatebin.net/?1ad339dfbe397783#9t7N6kAzgBUufrreHTv1pxQ8MNCvRw2AWAaYGY1jydzu