Well this is puzzling.
First thing there are a lot of errors displaying in the consoler, if you Right Click and Inspect and view the console tab. They need to be corrected at some point.
The issue i see is the #Document (Root Document) – which is the top level container that the entire page is loaded into is being displayed at several thousand pixels in width. The only javascript i can find that is doing anything with the #document is the mailchimp popup.
There must be a conflict either plugin related or any custom code that has been added.