Add selector for first page tree link in case no other submenu item was declared.

app/assets/javascripts/specific/main_menu.js.erb

@@ -57,7 +57,7 @@ jQuery(document).ready(function($) {
         $(".menu_root li").removeClass('open')
         $(".menu_root").removeClass('open').addClass('closed');
         target.closest('li').addClass('open');
-        target.closest('li').find('li > a:first').focus();
+        target.closest('li').find('li > a:first, .tree-menu--title:first').first().focus();
       }
       return false;
     });

frontend/src/app/components/resizer/main-menu-toggle.service.ts

@@ -165,7 +165,7 @@ export class MainMenuToggleService {
             // activeElement is outside of main menu.
             that.closeMenu();
           }
-        }, 100);
+        }, 0);
       }
     });
   }