function randHeader(){
	var hdr = document.getElementById('top_header');
	var hdrImgs = Array();
	hdrImgs[0] = 'ylakuva01.jpg';
	hdrImgs[1] = 'ylakuva02.jpg';
	hdrImgs[2] = 'ylakuva03.jpg';
	var selected = Math.floor(Math.random()*hdrImgs.length);
	hdr.style.backgroundImage = 'url("/static/gfx/'+hdrImgs[selected]+'")';
	//(selected +' '+ hdrImgs[selected]);
}