JQUERY Ninja menu wont collapse :-(

Just bought jquery Novice to Ninja and in chapter 5 I worked through the Expandabale/Collapsible Menus on page 136. Here is the work live:

But i just cant get the menu to collapse. I susoect I’m just not getting how to hook up the HTML to the jscript library.

If anyone could offer any insight into how I could get the collapsible menus to work it may just save me from by boss attaching electrically charged clamps to sensitive areas of my body :wink: