document.createElement('header');
document.createElement('footer');
document.createElement('section');
document.createElement('aside');
document.createElement('article');
document.createElement('nav');

$(document).ready(function(){
    $('.sub-menu').hide();
    
	
    $('#topnav li').mouseover(function(){
        
        var dropdown = $(this).children('.sub-menu');

        dropdown.slideDown('fast');
        
        $(this).mouseleave(function(){
                dropdown.slideUp('fast');
        }); 
    });
});