This screen shot is taken from a Virtuozzo Power Panel, which despite my complaints here, has some nice features for managing a VPS.

As you can see they use a light shade of red for the red zone, and then red for the black zone. At least they are using yellow for the yellow zone - but what is the difference between each zone, I'm guessing that the black zone is the worst (meaning my resources are low), but it just is a very confusing color scheme.

Above is a screen shot example of the coloring in use. The table header, and alternating row coloring don't help things. Also notice the black text on red background - a color contrast no no.