[Theme:Raider by Genesis] Make whole website full screen

Alright so I’m sure this is a fairly easy fix as well. I’m not very good with code and this theme isn’t very well documented so I thought I’d ask some of you experts here about how to take away that grey area in the background and simply make the whole website full width. I still want the sidebars, though. Is there an easy fix for this that will just make the header, footer, navigation, sidebar, and content areas full width? I have messed around a bit with the CSS but I’m not going into the php files because I don’t want to mess something up with my site.

Here’s my URL: https://www.thepeacetribe.com.

Thanks in advance for your help!