Hi Hiphopruckus,
To get back the grey space between main content and footer area in the Hueman theme, you need to get rid of the boxed layout.
To do so, go to Appearance > Theme Options. From here select the Styling tab (the last in the list). Once in the Styling section, find Boxed Layout (second option from the top) and select OFF. Save your changes, and you should be OK.
I hope this helps.
Cheers!
- Maria Antonietta