diff --git a/agaric/templates/layout/region--primary-menu.html.twig b/agaric/templates/layout/region--primary-menu.html.twig
new file mode 100644
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+++ b/agaric/templates/layout/region--primary-menu.html.twig
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+{#
+/**
+ * @file
+ * Default theme implementation to display a region.
+ *
+ * Available variables:
+ * - content: The content for this region, typically blocks.
+ * - attributes: HTML attributes for the region <div>.
+ * - region: The name of the region variable as defined in the theme's
+ *   .info.yml file.
+ *
+ * @see template_preprocess_region()
+ *
+ * @ingroup themeable
+ */
+#}
+{% if content %}
+  <div class="is-fixed">
+    {{ content }}
+  </div>
+{% endif %}