Change extra text font color

First I would like to say thanks for the great work on Mantra themes. Tried several themes before coming across Mantra, just great, love it.

I have everything good except I would like to change the background color for the extra test box at the bottom of presentation page and also the font color within the box. I’m not real familiar with CSS but have managed to change a few things using custom CSS built into Mantra and searching on this forum. Is that where this change needs to go, custom CSS?