function show(element, klasse) {
	document.getElementById(element).className = klasse;
}
function hide(element, klasse) {
	document.getElementById(element).className = klasse;
}

function flip(element) {
	if(document.getElementById(element).className == 'on') {
         	document.getElementById(element).className = 'off';
         } else {
         	document.getElementById(element).className = 'on';
         }
}