chore(docs-app): improve layout when loading partials

By setting the current partial content to hidden, the current height
of the window is maintained until the new content is loaded.
This prevents flickering caused by the scrollbar (dis)appearing and
the footer coming into view.

Author: Narretz

docs/app/assets/css/docs.css

@@ -653,6 +653,13 @@ ul.events > li {
   max-width: 100%;
 }
 
+@media only screen and (min-width: 769px) {
+  [ng-include="partialPath"].ng-hide {
+    display: block !important;
+    visibility: hidden;
+  }
+}
+
 @media only screen and (min-width: 769px) and (max-width: 991px) {
   .main-body-grid {
     margin-top: 160px;