Leaflet/mapbox opacity test

gistfile1.txt

<link rel="stylesheet" href="dist/leaflet.css" />
<!--[if lte IE 8]>
    <link rel="stylesheet" href="dist/leaflet.ie.css" />
<![endif]-->
<script src="dist/leaflet.js"></script>
<style>
    #map {
        width: 100%;
        height: 100%;
        position: absolute;
        top: 0px;
        left: 0px;
        right: 0px;
        bottom: 0px;
    }
</style>
<div id="map"></div>
<script>
    var map = L.map('map')
            .setView([43.6654, -79.4775], 15);

    var base = L.tileLayer('http://{s}.tile.mapbox.com/v3/examples.map-vyofok3q/{z}/{x}/{y}.png')
            .addTo(map);

    var overlay = L.tileLayer('http://{s}.tile.mapbox.com/v3/aibram.Aerial/{z}/{x}/{y}.png')
            .addTo(map);

    overlay.setOpacity(0.6);
</script>