var speed = 300 /* You can define the speed of the animation, in milliseconds (1000 = 1sec) */
$(document).ready(function(){	
	$('.mainnav ul li').hover(function(){ 
			//$(this).find('div:first').css({visibility: "visible",display: "none"});
			$(this).find('div:first').css({visibility: "visible",display: "none"}).fadeIn("400", 'swing');
       },function(){ 
        //$(this).find('div:first').css({visibility:"hidden"}).slideToggle(speed);
		$(this).find('div:first').css({visibility:"hidden"}).fadeOut("100", 'swing');
   });	
});