So here’s a codepen, however, the JS function seems to have broken:
http://codepen.io/jgclifton/pen/ohplL
Am example on my webserver is http://notfilc.eu/oxweb2/
So here’s the problem. When going in to a mobile view (make browser small), I set the navigation to display none and use some JS to toggle this.
However, if you are on a device such as a tablet, and you start off in the small view, and then switch to the bigger view (by changing the orientation), then the menu will not be there.
Any ideas? hope this makes sense!