// centrovanie
function center_t(h){
	t=(screen.height-h)/2;
	return t;
}
function center_l(w){
	l=(screen.width-w)/2;
	return l;
}

// thumb
function thumb_on(id){
	id_obj="foto_t_"+id;
	document.getElementById(id_obj).className="foto_t foto_t_up";
	id_obj="t_foto_"+id;
	document.getElementById(id_obj).className="t_foto t_foto_up";
}
function thumb_off(id){
	id_obj="foto_t_"+id;
	document.getElementById(id_obj).className="foto_t";
	id_obj="t_foto_"+id;
	document.getElementById(id_obj).className="t_foto";
}