fix editor width for not found page

src/client/styles/scss/_layout.scss

@@ -6,6 +6,10 @@ body:not(.growi-layout-fluid) .grw-container-convertible {
   @extend .container-lg;
 }
 
+body.not-found-page .grw-container-convertible {
+  @extend .container-lg;
+}
+
 body.growi-layout-fluid .grw-container-convertible {
   @extend .container-fluid;
 }

src/server/views/layout-growi/not_found.html

@@ -1,15 +1,16 @@
 {% extends 'base/layout.html' %}
 
+{% block html_base_css %}not-found-page{% endblock %}
 
 {% block content_main_before %}
-  <div class="container-lg">
+  <div class="grw-container-convertible">
     {% include '../widget/page_alerts.html' %}
   </div>
 {% endblock %}
 
 
 {% block content_main %}
-  <div class="container-lg">
+  <div class="grw-container-convertible">
     {% include '../widget/not_found_content.html' %}
   </div>
 {% endblock %}