Use mapbox

map.html

@@ -54,8 +54,8 @@
 
     $(document).ready(function() {
       var map = L.map('map').setView([51.0475378, 3.7261835], 13);
-      var osm = L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
-        attribution: 'Made by <a href="http://zeus.ugent.be">Zeus</a> with ❤!'
+      var osm = L.tileLayer('https://{s}.tiles.mapbox.com/v3/feliciaan.keoaj8d5/{z}/{x}/{y}.png', {
+        attribution: 'Made by <a href="http://zeus.ugent.be">Zeus</a> with ❤ and <a href="http://www.mapbox.com/about/maps/" target="_blank">Terms &amp; Feedback</a>'
       }).addTo(map);
 
       $.getJSON('data.json')