function mainmenu(){
$(" #nav ul ").css({display: "none"});
$(" #nav li").hover(function(){
		$(this).find('ul:first').css({visibility: "visible",display: "none"}).show(400);
		},function(){
		$(this).find('ul:first').css({visibility: "hidden"});
		});
}

$(document).ready(mainmenu());