markdown plugin around markdown includes

docs/css.html

@@ -11,7 +11,11 @@ lead: "Global CSS settings, fundamental HTML elements styled and enhanced with e
 {% include css/code.html %}
 {% include css/tables.html %}
 {% include css/forms.html %}
-{% include css/buttons.html %}
-{% include css/images.html %}
-{% include css/helpers.html %}
+
+{% markdown %}
+  {% include css/buttons.md %}
+  {% include css/images.md %}
+  {% include css/helpers.md %}
+{% endmarkdown %}
+
 {% include css/responsive-utilities.html %}