Their study involved using images to collect their data — a good way to get fairly reliable numbers.
I didn’t know what an off-canvas navigation menu was until working on a project at my current job. It’s the little three horizontal line button often seen in mobile web site and mobile applications. When you tap/click it, it slides the content to the left and a menu pushes out from the left (or off canvas).
Anyway, I had used a plugin called sidr on said project and got it to work. On the next project though, I might look into using Pushy, self-described as “a responsive off-canvas navigation menu using CSS transforms & transitions.”
It does add one other dependency on top of jQuery — Modernizr, which isn’t a bad thing to be utilizing anyway.