diff --git a/agaric/templates/layout/ds--2col--node-landing-page-simple-card.html.twig b/agaric/templates/layout/ds-2col--node-landing-page-simple-card.html.twig
similarity index 100%
rename from agaric/templates/layout/ds--2col--node-landing-page-simple-card.html.twig
rename to agaric/templates/layout/ds-2col--node-landing-page-simple-card.html.twig
diff --git a/agaric/templates/layout/ds-2col.html.twig b/agaric/templates/layout/ds-2col.html.twig
index ab7ee3c..552985f 100644
--- a/agaric/templates/layout/ds-2col.html.twig
+++ b/agaric/templates/layout/ds-2col.html.twig
@@ -14,15 +14,15 @@
  * - right: content of right region
  */
 #}
-<{{ outer_wrapper }}{{ attributes.addClass('clearfix') }}>
+<{{ outer_wrapper }}{{ attributes.addClass('columns', 'clearfix') }}>
 
   {{ title_suffix.contextual_links }}
 
-  <{{ left_wrapper }}{{ left_attributes.addClass('') }}>
+  <{{ left_wrapper }}{{ left_attributes.addClass('column') }}>
     {{ left }}
   </{{ left_wrapper }}>
 
-  <{{ right_wrapper }}{{ right_attributes.addClass('') }}>
+  <{{ right_wrapper }}{{ right_attributes.addClass('column') }}>
     {{ right }}
   </{{ right_wrapper }}>