How to do css

so in your edit pf at the bottom theres a place for css Idk how to make your own css but ik some people have tutorials on it but what I did was use some pre made ones heres where I got mine css credit https://sophiezhng.github.io/my-space-windows-93-themes/ just copy all of the css and then paste it in to the spot on your edit pf thing and thats it hope that helps