What I mean is, almost all of the colors are hard coded, unlike primaryButtonColor. You can easily adjust that one, but the others are trickier.
The newest version of variables.less in the 2.0 wip branch seems to have these colors bubbled up to easier access, already, now that I look at it. But still, the buttons aren't all exposed - just the primary button. That's what I was suggesting.
You can always change and recompile.