Add a progress and a text and put it in a shortcode

content/multipledataset.html

@@ -328,4 +328,4 @@ draft: false
     <div id="graph_div"></div>
   </table>
 </div>
-<div class="modal"></div>
+{{< waitModal >}}

content/onedataset.html

@@ -200,4 +200,4 @@ draft: false
       </table>
     </div>
     </p>
-    <div class="modal"></div>
+    {{< waitModal >}}

layouts/shortcodes/waitModal.html

@@ -0,0 +1,7 @@
+<div class="modal">
+  <div class="content">
+    <span>Please Wait…</span>
+    <br/>
+    <progress></progress>
+  </div>
+</div>

static/css/modal.css

@@ -27,4 +27,11 @@ body.loading .modal {
 body.loading .modal {
     display: block;
     cursor: wait
+}
+.modal .content {
+  position: absolute;
+  left: 50%;
+  top: 50%;
+  -webkit-transform: translate(-50%, -50%);
+  transform: translate(-50%, -50%);
 }