jQuery(document).ready(function(){

  var timerid;

  jQuery("#dropdown li").hover( function(){
    jQuery(this).children("ul").css('opacity',0).animate({
      opacity:1,
      height:'show'
    },400);
  }, function(){
    jQuery(this).children("ul").animate({
      opacity:0,
      height:'hide'
    },400);
  });
});