Custom color background

[Icemoon 3]

Currently we just have white and dark gray as background choices. Very dark or white backgrounds both bother my eyes.

Can we get custom colors or at least options that are less stark? 

Instead of bright white, something in the cream to parchment spectrum?  Instead of gray or black, muted blues or greens? 

Or let us choose our own, ideally. 

Thanks for reading.