In your example you used red because of the color of your header?
Are you talking about something based on the color of the main tag? If so, think about the "rainbow" that we'll have on the homepage if something like this will be made.
Don't get me wrong, I totally agree that they should be different in a way that pops out, but I think a slightly different background will do the trick newt to the sticky icon that's added automatically. I hope that this was your idea too, and not something based on the main tag as I said above ?
