diff --git a/theme/templates/macros/cards.html b/theme/templates/macros/cards.html
index f6507967c16a0788c3a48cf51e7de2cc7bf076b5..df5542bfce6e18160b8bcdddf0932ef2b42f01a7 100644
--- a/theme/templates/macros/cards.html
+++ b/theme/templates/macros/cards.html
@@ -1,6 +1,7 @@
 
-{%- macro open(id = None, classes = None) -%}
-	<ul {%- if id %} id="{{ id|e }}"{% endif %} class="cards {%- if classes %}{% for class in classes %} {{ class|e }}{% endfor %}{% endif %}">
+{%- macro open(id = None, classes = []) -%}
+	{%- set attr = {"id": id, "classes": classes} -%}
+	<ul {{ common.render_attr(attr, None)}}>
 {%- endmacro -%}
 
 {%- macro close() -%}