$(function(){
    $('#top_menu').each(function(){
      var obj=$(this);
      var mis=obj.find('>ul>li');
      mis.each(function(){
        var mi=$(this);
        var smenu=mi.find('.submenu');
        if (smenu.length)
        {
          var height=smenu.height();
          smenu.height(0).css({display:'block'});
          mi.mouseenter(function(){
            smenu.stop(true,false).animate({height:height+'px'},{easing:'swing',duration:250});
          });
          mi.mouseleave(function(){
            smenu.stop(true,false).animate({height:0+'px'},{easing:'swing',duration:250});
          });
        }
      });
    });
  });