diff --git a/templates/page.html b/templates/page.html
index 5eb0609..096f386 100644
--- a/templates/page.html
+++ b/templates/page.html
@@ -98,7 +98,8 @@
   {% endif %}
 
   <!-- giscus comment -->
-  {% if config.extra.giscus.repo and page.extra.comments %}
+  {% if page.extra.comment | default(value=config.extra.comment) %}<!---->
+  {% if config.extra.giscus.repo %}
   <div class="giscus mt-12"></div>
   <script
     src="https://giscus.app/client.js"
@@ -117,6 +118,7 @@
     crossorigin="anonymous"
     async
   ></script>
+  {% endif %}<!---->
   {% endif %}
 </article>
 {% endblock main %}
diff --git a/templates/partials/head.html b/templates/partials/head.html
index ac3606b..0a0a6d2 100644
--- a/templates/partials/head.html
+++ b/templates/partials/head.html
@@ -60,7 +60,7 @@
   <!---->
 
   <!-- Mermaid -->
-  {% if page.extra.mermaid %}
+  {% if page.extra.mermaid | default(value=config.extra.mermaid) %}
   <script type="module">
     import mermaid from "https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.esm.min.mjs";
     mermaid.initialize({ startOnLoad: true });