Assign CSS classes and id to the entire module, but not for each button specifically.

Is there any other work around for triggering? I'm using the Divi theme and there is this Fullwidth Header Module and it has two buttons. But I can only assign CSS classes and id to the entire module but not for each button specifically. I'm trying to find a way to use those buttons for the popup trigger anyway... Do you see any option?

Eg., http://wenetwork.wpengine.com/buchung/ the left Login button