Columns not Collapsing for Mobile Display

Hello,

I’ve built a site using WooCommerce, Storefront Theme & SiteOrigin. { www.handygardenmachineryltd.co.uk } For reference.
I’ve experienced two problems,
The first is the content on the Homepage doesn’t display across the full width of the div. Looking at the CSS there is a max-width setting somewhere but I cannot see where this could be changed.

Secondly, The content does not collapse down on a mobile device, the text columns adjust to the screen size (Left to right) but never change to Top & Bottom like I think they should.

Thanks in advance for your help.