diff --git a/agaric/templates/container.html.twig b/agaric/templates/container.html.twig
index ec1b750..60a8fe7 100644
--- a/agaric/templates/container.html.twig
+++ b/agaric/templates/container.html.twig
@@ -1,3 +1,4 @@
 {% extends "@stable/form/container.html.twig" %}
-
-{% set attributes = attributes.addClass("field") %}
+{# TODO this should never be both at once, so a huge TODO is to add template
+   suggestions for the container template.  Right now there are *none* #}
+{% set attributes = attributes.addClass(["field", "container"]) %}