$(document).ready(function() {
	$("#menu_nav ul.listmenu").children("li").children("ul").css("display","none");
	$("#menu_nav ul.listmenu").children("li").hover(
	  function () {
		$(this).children("ul").slideDown("fast");		
	  },
	  function () {
		$(this).children("ul").slideUp("fast");	
	  }
	);
});