Fade the map in after it is done loading

public/index.html

@@ -143,6 +143,10 @@
         </fieldset>
       </div>
 
+      <div class="map-placeholder">
+        Loading...
+      </div>
+
       <object type="image/svg+xml" data="map.svg"></object>
 
       <div id="status">

public/style.css

@@ -16,6 +16,11 @@ svg, object {
   height: 100%;
 }
 
+object {
+  opacity: 0;
+  transition: opacity 0.25s;
+}
+
 svg image {
   image-rendering: pixelated;
 }