var menu = "none";
 function show_menu(menu){	//show submenu and submenu choices
    document.getElementById(menu).style.display = '';	
 }
 function hide_menu(){	//hide submenu and submenu choices
	if ((document.getElementById('about').style.display == '')) {
      	document.getElementById('about').style.display = 'none';
	}
	if ((document.getElementById('letsdance').style.display == '')) {
      	document.getElementById('letsdance').style.display = 'none';
	}
	if ((document.getElementById('learn').style.display == '')) {
      	document.getElementById('learn').style.display = 'none';
	}
 }