$(document).ready(function(){

$("#submenu").css({visibility: "hidden"});
function mainmenu(){
$("#menu ul li").hover(function(){	
		$(this).find('#submenu').css({visibility: "visible",display: "none"}).show(300);
		},function(){
		$(this).find('#submenu').css({visibility: "hidden"});
		});
}
mainmenu();

});