Margin Issues

[arimcw]

Hello to all!
I want to start off by thanking you of taking the time to read my help request.
That said, I have issues on my site concerning margins being too large. It would be great if the website could occupy the whole screen. The issue is worst on mobile devices.
You will find attached pictures of the issue, as well as the link & password. 
Many thanks,

Ariel

https://syndromeca.com
password: gyatemala