None of the dark themes work properly

Hi there, I have seen different instructions on here for how to get custom themes working, and they involve setting custom paths and all this. I just want to mention that I can get dark themes loading, it’s just that they never load all the way.

Sometimes, they’ll just make the header dark and nothing else. Some of them make all the form elements dark, and change the color of buttons and nothing else. So obviously the css is loading, it’s just not overriding defaults. Does anyone have any ideas how to make these dark themes truly work?