Update 404 page

Text is now center-aligned

_layouts/404.html

@@ -20,4 +20,9 @@
             {% include footer.html %}
         </div>
     </body>
+    <style>
+        .mdc-top-app-bar--short-fixed-adjust {
+            text-align: center;
+        }
+    </style>
 </html>