I thought I could choose Flat Dark and then customize a color scheme to my taste (I wanted a slightly lighter background for the editor panel). I'm having some trouble making that work properly. A pathological case is taking my default custom scheme (which has a white background) and using it with Flat Dark, which results in

I expected to end up with a white background in the editor panel, at which point I could have darkened it to my taste.
The problem here is that the user has no control over such things as the Code Explorer and File Explorer.