old_contents: var southWest = L.latLng(34.9816, -85.4719);
  var northEast = L.latLng(35.217, -85.0462);
  var center = L.latLng(35.0657, -85.241);
  var bounds = L.latLngBounds(southWest, northEast);
  
  var map = L.map('map', {
    maxZoom: 18,
    minZoom: 11,
    maxBounds: bounds,
    center: center,
    zoom: 12
  });
  
  L.tileLayer('http://chattanoogapubliclibrary.github.io/cpd-zones-tiles/tiles/{z}/{x}/{y}.png', {
      attribution: 'Map data &copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, <a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, Zone data &copy; City of Chattanooga, Imagery © <a href="http://mapbox.com">Mapbox</a>'}).addTo(map);
  
  r
  
new_contents: var southWest = L.latLng(34.9816, -85.4719);
  var northEast = L.latLng(35.217, -85.0462);
  var center = L.latLng(35.0657, -85.241);
  var bounds = L.latLngBounds(southWest, northEast);
  
  var map = L.map('map', {
    maxZoom: 18,
    minZoom: 11,
    maxBounds: bounds,
    center: center,
    zoom: 12
  });
  
  L.tileLayer('//chattanoogapubliclibrary.github.io/cpd-zones-tiles/tiles/{z}/{x}/{y}.png', {
      attribution: 'Map data &copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, <a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, Zone data &copy; City of Chattanooga, Imagery © <a href="http://mapbox.com">Mapbox</a>'}).addTo(map);
  
  r
  
subject: Change tile URL to work with HTTP or HTTPS.