styling positions

Here is the deal...
I want to assign different id's to each positions in my layout.

For example:
I got 3 spotlight positions at the bottom of my site. I want to assign 3 different ID's to spotlight-4, spotlight-5 and spotlight-6.

Actually, I want to add a border-bottom to module titles, but each position should have a different border color.
I can style the class "module-title" to add the border-bottom, but I don't know how to set different colors for each position. Is that possible?

Thanks.