--- a/_includes/footer.html	Wed Sep 28 11:30:27 2016 +0200
+++ b/_includes/footer.html	Wed Sep 28 21:51:37 2016 +0200
@@ -13,4 +13,18 @@
     x.className = "topnav";
   }
 }
+
+function openCity(evt, cityName) {
+  var i, tabcontent, tablinks;
+  tabcontent = document.getElementsByClassName("tabcontent");
+  for (i = 0; i < tabcontent.length; i++) {
+    tabcontent[i].style.display = "none";
+  }
+  tablinks = document.getElementsByClassName("tablinks");
+  for (i = 0; i < tablinks.length; i++) {
+    tablinks[i].className = tablinks[i].className.replace(" active", "");
+  }
+  document.getElementById(cityName).style.display = "block";
+  evt.currentTarget.className += " active";
+}
 </script>