function add_class_name(element, class_name) {
	
	var current_class_name = element.className;
	var pattern = '/' + class_name + '/';
	var regex = new RegExp(pattern);
	
	if (!regex.test(current_class_name)) {
		if (current_class_name == '') {
			current_class_name = class_name;
		} else {
			current_class_name += ' ' + class_name;
		}
	} 
	
	element.className = current_class_name;
	
}

function remove_class_name(element, class_name) {

	var current_class_name = element.className;
	var pattern = '/' + class_name + '/';
	var regex = eval(pattern);
	
	current_class_name = current_class_name.replace(regex, '');
			
	regex = new RegExp('/ +/');
	current_class_name.replace(regex, ' ');

	element.className = current_class_name;
}