Too Much Space When Viewed on iPhone

I am having trouble with the Realtor theme from SMThemes. After building the site nearly a year ago, I have never viewed it on the iPhone, but my boss says he has viewed it regularly. Recently, when he opened the site, the page shows as half width on the iPhone with the right side of the screen taken by black space. The only element that seems to span the entire width of the phone is the footer, but I cannot alter the footer without getting an error message due to the free template.

Since this seems to be a recent change, it must be something I have done, but all I have done in the last few weeks is upgrade the plug-ins. I have disabled all of them yet the problem still exists. The site is here:

https://www.elegantposts dot com

Other themes are working as they should and I have sent this issue to SMThemes, but since it is a free template, I am not sure what I will get for help.