first, hoverIntent is jQuery plugin so you need to add jQuery to jsfiddle
second, you cannot use plugin before its code implemented, it is also about horizontal menu
third, you cannot use functions that are not yet declared so makeTall
and makeShort
must be declared before hoverIntent(makeTall,makeShort)
fourth, you dont need to mouseenter/leave inside makeTall/makeShort, hoverIntent already does everything you need
working feedle