I added a box shadow to the card element on my forum just to give a little distinction between the forum and the background.
I also like the look it gave to the memberlist.

Before:

 

After:

 

Your ‘search for a user’ JS looks broken in that image. Have you been editing the templates or has it been like that since you uploaded it?

Oops. Forgot to add the select2 css.
All fixed.