$(document).ready(function(){

    //When mouse rolls over
    $("#mainNav>li").mouseover(function(){
        $(this).stop().animate({height:'180px'},{queue:false, duration:1200, easing: 'easeOutQuint'})
    });

    //When mouse is removed
    $("#mainNav>li").mouseout(function(){
        $(this).stop().animate({height:'31px'},{queue:false, duration:1200, easing: 'easeOutQuint'})
    });

});