function changeClass(element, className){
    if (element.className.search(className) == -1) 
	{
		element.className += ' ' + className;
	} 
	else 
	{
		element.className = element.className.replace(className,'');
	}
}  

function changeState (element){
	if (element.getElementsByTagName('ul').length == 0) changeClass(element, 'single');
	else changeClass(element, 'opened');
}

function setImageMargin(){
	var spanArray = document.getElementsByTagName('span');
	var spanArraylength = spanArray.length;
	for (var i = 0; i < spanArraylength; i++)
	{
		if (spanArray[i].className == 'img_border')
		{
			var img = spanArray[i].getElementsByTagName('img')[0];
			img.style.marginTop = (73 - img.offsetHeight)/2 + 'px';
		}
	}
}