function removeUnvisibleElements(container,tagName,css_class){
	var nodes=container.getElementsByTagName(tagName);
	for(var i=0;i<nodes.length;i++) 
		if(nodes[i].style.display.toLowerCase()=='none' && (css_class==null || nodes[i].className.indexOf(css_class)!=-1))
			nodes[i].parentNode.removeChild(nodes[i]);
		else removeUnvisibleElements(nodes[i],tagName,css_class);
}