Would be really great for some of us who look at screens all day to get a night theme that's actually dark. You could name it/make it themed around the amount of light present in any given biome during a new moon, or perhaps what night would be like under a dense canopy.

The actual UI elements could be something as simple as using dark greys and/or black. Text could be high contrast white, but it would probably be preferable to keep it a softer off-white or very light grey.