I know you want this to look like a Game Boy title, but consider that those games were optimized for a screen without a backlight. All of that white will be pretty glaring on a bright computer display. You could invert the window skin and font colors.
In my experience GB games always came out a bit green looking, sorta like Wither's style I guess. It'd be a bit less harsh to look at, not that I minded the bright white when I played a little bit before. :P
Is it at all possible to change the font though? I think that was my only real issue with the aesthetic - it was otherwise perfection!