Unable to change background colour for JPhotolio theme

Hey Guys,

I’m looking for help on trying to change the background colour of each of my pages from white to black.

The website is for my photo booth rental company PhotoCorner.ca

I’ve tried almost everything!

-I checked through every single setting in the JPhotolio theme settings.
-I tried adding custom CSS to the style.css page
-I tried adding HTML code to each individual page

Any help would be greatly appreciated!