Extension Update! Thanks to the awesome @OrdinaryJellyfish who showed me how to append css code to the head in js, my extension now does something!
Right now, it looks really bad because it styles all the elements the same color, so working on that.
I also haven't updated the admin js files, just been working on the forum ones, so the actual admin side doesn't get styled. Still deciding whether it should or not. Razor I think I am going to add different fields, that way the whole site doesn't end up the same color. I might also take @Pollux advice on my other post at https://discuss.flarum.org/d/9475-global-css-selector/15 and requiring a RGB code, then using the styling that was supplied. Any tips are appreciated!