remove white space from left/right side..want full screen throughout the page

I’ve been playing around with this theme a few days now. at first the full page was all full screen and then all of a sudden there was white spage on both the right and left side. It’s not because its on a computer v mobile because you can see the white space on both. I need code to enter into the HIghend options-> General settings-> custom css to reduce the margins on the side. Any help would be appreciated. I have the Highend theme using the landing page/startup demo.

See screen shot attached for left and right white margins.

Thanks!