diff --git a/agaric/templates/block/block--system-menu-block--main.html.twig b/agaric/templates/block/block--system-menu-block--main.html.twig
index 14370a5..a71ce83 100644
--- a/agaric/templates/block/block--system-menu-block--main.html.twig
+++ b/agaric/templates/block/block--system-menu-block--main.html.twig
@@ -1,3 +1,10 @@
 {% extends "@bulma/block/block--system-menu-block.html.twig" %}
 
-{% set attributes = attributes.addClass('navbar-end') %}
+{%
+  set classes = [
+    'navbar-end',
+    'navbar',
+  ]
+%}
+
+{% set attributes = attributes.addClass(classes) %}