Implement a switch for switching between light and dark mode

blog/templates/edition-3/foundation.html

@@ -41,6 +41,8 @@
         </footer>
     </div>
 
+    <div class="light-switch" onclick="toggle_lights()"></div>
+
     <!-- Fathom - simple website analytics - https://github.com/usefathom/fathom -->
     <script>
         (function(f, a, t, h, o, m){

blog/templates/edition-3/page.html

@@ -98,7 +98,7 @@
         </p>
         {% endif %}
 
-        {{ macros::utterances() }}
+        {{ macros::utterances_edition_3() }}
     </section>
 
     <aside class="page-aside-right">

blog/templates/macros.html

@@ -54,6 +54,17 @@
     </script>
 {% endmacro utterances %}
 
+{% macro utterances_edition_3() %}
+    <script src="https://utteranc.es/client.js"
+        data-repo="phil-opp/blog_os"
+        data-issue-term="url"
+        data-label="comments"
+        crossorigin="anonymous"
+        theme="preferred-color-scheme"
+        async>
+    </script>
+{% endmacro utterances_edition_3 %}
+
 {% macro toc(toc) %}
     <details id = "toc-inline">
         <summary><b>Table of Contents</b></summary>