function RandomHeader(tag, container) {
	this.container = $(container);
	this.items = this.container.getElementsByTagName(tag);
	
	var randNum = Math.floor(Math.random() * (this.items.length));
	for (var i=0, item; item=this.items[i]; i++) {
		if (i==randNum) {
			this.items[i].className = 'active';
		} else {
			this.items[i].className = '';
		}
	}
}

RandomHeader('img', 'randomheader');