add container

src/server/views/widget/page_content.html

@@ -1,5 +1,5 @@
 {% if page %}
-<div id="content-main" class="content-main"
+<div id="content-main" class="content-main container"
   data-path="{{ encodeURI(page.path) }}"
   data-current-user="{% if user %}{{ user._id.toString() }}{% endif %}"
   data-page-id="{% if page %}{{ page._id.toString() }}{% endif %}"