I slaved over getting the css right for hours (mostly figuring css out) about a year ago. Today an update to the theme droped and overwrote my changes, breaking the dark variant (the header and every alternate field reverted to a light background). I hacked in a quick fix to at least return it to being dark, but IDK what the original color values were.
Tl;dr if you either have a better grasp of contrast than me (you probably do) or you have the old values handy (wayback machine?), feed em to me as hex rgb values and I’ll patch em in.
Alternately you might have just been looking at it when I was scrambling to fix it.