Body gets clipped on sides at iphone size

I'm having an issue with the body of the site getting clipped on the sides at smaller screen sizes. It's like there's a "minimum-width" setting somewhere. It's a single-page site, I've used sections in the single page and set all of them to full width.
The header is resizing fine down to very small width. Just not the body.

I'm also not understanding why customize/layout/container doesn't have a "full width" option. Is that because setting page body elements to "full" effectively bypasses the container width?

See apdcnc.com

Thanks!