Application theme options

While I adore the color options for the themes, the issue for me is the boxes where most of my attention would be (chapter stuff, writing window, all the cards, etc.) Which means in the end, the options are staring into the sun (ie, white boxes) or staring into the void. (black/very dark boxes.)

Could there be a middle ground? Or a way for us to pick our own box background colors/gradiations separate from the them? I would like my typing space to be something between white and a few shades off black. Maybe pick the font colors to get the contrast needed to make it easier to work with for long periods of time.