On a smartphone, the menu on this site wouldn't scroll down to menu items near the bottom of the menu, e.g. Hobbies -> Motorcycles -> '08 Honda Fireblade.
This turned out to be a known bug, with a workaround (which I have of course implemented on this site).
More info can be found at https://community.oracle.com/thread/4154305, with the workaround by Shakeeb Rahman:

Here is a workaround you can try while we prepare a proper fix for this behavior.
This workaround will completely disable TouchProxy (a handler we use to intercept touch events and add touch support for jQuery UI widgets). Please add this code to Function and Global Variable Declaration page attribute: apex.widget.util.TouchProxy.addTouchListeners = function() {}; apex.widget.util.TouchProxy.removeTouchListeners = function() {};