Changing background colors in every passage

I am using sugarcube and I want to make the background change color gradually in every new passage, getting slightly brighter or darker depending on the path the player is following. Every single passage would be a (slightly) different color. I've been using <<addclass>> to put different colors in each passage, but I'm wondering if there's a way I can do that without having to make a new class each time, because that takes up a ton of room in the stylesheet and is very time consuming.

Thanks