message: fix(docs-infra): fix sidenav positioning when notification is shown
  _Before:_
  ![sidenav-scrollbar-before](https://user-images.githubusercontent.com/8604205/49089078-62519d00-f263-11e8-8369-f39e73dcc239.png)
  _After:_
  ![sidenav-scrollbar-after](https://user-images.githubusercontent.com/8604205/49089077-62519d00-f263-11e8-8a94-0c34044c4ba1.png)
  PR Close
diff: @@ -73,7 +73,7 @@ aio-notification {
  }
  mat-sidenav.mat-sidenav.sidenav {
  - top: 56px + $notificationHeight;
  + top: 64px + $notificationHeight;
  @media (max-width: 600px) {
  top: 56px + $notificationHeight;
  