When you open the hamburger menu in preview mode on a site I'm working on it it kills all interactions on that page unless you click a link from the menu. So if you open and close the hamburger without clicking a link and going to a new page, you can't do anything on that page.
Here is a preview link:
Any ideas as to the culprit? Any help would be much appreciated.
[UPDATE] using firebug to inspect it appears that w-nav-overlay stays open and stops you from interacting with other elements?