I played around in Profile Customizer Administration a bit. I added new css for description. This is what I did....
Name: Description
Catption: Description text
Name of css: #divUnderCustomization p
Type: Fonts
I tested and it does change the color just fine but when I made "Default box content" and "Default box full" transparent, I still see the whilte box behind the description. Any idea how to remove that? Here's the image below. This image is just a test.