shuffle = function(o){ //v1.0
	for(var j, x, i = o.length; i; j = parseInt(Math.random() * i), x = o[--i], o[i] = o[j], o[j] = x);
	return o;
};

$(function(){
	var shuffled_array = shuffle([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
	$("#kopfbild1").css("background", "url('/images/bildwechsler_" + shuffled_array[0] + ".jpg')");
	$("#kopfbild2").css("background", "url('/images/bildwechsler_" + shuffled_array[1] + ".jpg')");
	$("#kopfbild3").css("background", "url('/images/bildwechsler_" + shuffled_array[2] + ".jpg')");
	$("#kopfbild4").css("background", "url('/images/bildwechsler_" + shuffled_array[3] + ".jpg')");
});