CSS Menu clicked parameter?

[e_coli_lover]

I've got a css menu, using images as background, and roll over effects. I want to code the following: when an item is clicked it stays in the rollover state and returns back to the original when you click on another item...which in turn stays in roll over state etc. etc. Basically i want the user to know which page he/she is on by the way the navigation link looks.

There's gotta be a simple line or two of coding that does this. Can anyone please help?