Update dark mode and change the primary button color scheme

[Xalavar]

Added a few new things to dark mode. Also, personally, I don't think small-items.css should really be changing the color of the primary button, especially since it almost blends in with the background in dark mode.

[Thorvarium]

Hey, removing the black from the light mode and keeping the text white made it look weird. Just keep it in black in the normal mode and overwrite it to the yellow-wish in the dark mode

[Xalavar]

Should work now. I had to remove some of the important flags for small-items since dark mode can't take precedence with them there.

[Thorvarium]

There is one small error on the RFY/AFA/AI tabs when using the dark theme:

[Thorvarium]

Looking good now, thanks