Implement a switch for switching between light and dark mode

blog/sass/css/edition-3/main.scss

@@ -88,6 +88,13 @@ html {
     --post-title-color: #c8c8ff;
 }
 
+@mixin light-switch-light {
+    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='%23004' class='bi bi-moon' viewBox='0 0 16 16'%3E%3Cpath fill-rule='evenodd' d='M14.53 10.53a7 7 0 0 1-9.058-9.058A7.003 7.003 0 0 0 8 15a7.002 7.002 0 0 0 6.53-4.47z'/%3E%3C/svg%3E");
+}
+
+@mixin light-switch-dark {
+    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='%23ff9' class='bi bi-brightness-high-fill' viewBox='0 0 16 16'%3E%3Cpath d='M12 8a4 4 0 1 1-8 0 4 4 0 0 1 8 0zM8 0a.5.5 0 0 1 .5.5v2a.5.5 0 0 1-1 0v-2A.5.5 0 0 1 8 0zm0 13a.5.5 0 0 1 .5.5v2a.5.5 0 0 1-1 0v-2A.5.5 0 0 1 8 13zm8-5a.5.5 0 0 1-.5.5h-2a.5.5 0 0 1 0-1h2a.5.5 0 0 1 .5.5zM3 8a.5.5 0 0 1-.5.5h-2a.5.5 0 0 1 0-1h2A.5.5 0 0 1 3 8zm10.657-5.657a.5.5 0 0 1 0 .707l-1.414 1.415a.5.5 0 1 1-.707-.708l1.414-1.414a.5.5 0 0 1 .707 0zm-9.193 9.193a.5.5 0 0 1 0 .707L3.05 13.657a.5.5 0 0 1-.707-.707l1.414-1.414a.5.5 0 0 1 .707 0zm9.193 2.121a.5.5 0 0 1-.707 0l-1.414-1.414a.5.5 0 0 1 .707-.707l1.414 1.414a.5.5 0 0 1 0 .707zM4.464 4.465a.5.5 0 0 1-.707 0L2.343 3.05a.5.5 0 1 1 .707-.707l1.414 1.414a.5.5 0 0 1 0 .708z'/%3E%3C/svg%3E");
+}
 
 body {
     @include set-colors-light();
@@ -97,6 +104,14 @@ body.dark {
     @include set-colors-dark();
 }
 
+.light-switch {
+    @include light-switch-light();
+}
+
+body.dark .light-switch {
+    @include light-switch-dark();
+}
+
 /* Styles for users who prefer dark mode at the OS level */
 
 @media (prefers-color-scheme: dark) {
@@ -108,8 +123,15 @@ body.dark {
     body.light {
         @include set-colors-light();
     }
-}
 
+    .light-switch {
+        @include light-switch-dark();
+    }
+
+    body.light .light-switch {
+        @include light-switch-light();
+    }
+}
 
 body {
     color: var(--text-color);
@@ -942,4 +964,21 @@ a strong {
 
 .left-to-right, .right-to-left pre {
     direction: ltr;
-}
+}
+
+.light-switch {
+    position: fixed;
+    left: 2rem;
+    bottom: 2rem;
+    background-repeat: no-repeat;
+    width: 2rem;
+    height: 2rem;
+    cursor: pointer;
+    opacity: 0.6;
+}
+
+.light-switch:hover {
+    transform: scale(1.3);
+    transition: 200ms ease-out;
+    opacity: 1;
+}

blog/static/js/edition-3/main.js

@@ -61,3 +61,29 @@ function toc_scroll_position(container) {
     current_toc_item.classList.add("active");
   }
 }
+
+function toggle_lights() {
+  var body = document.querySelector("body");
+  var comment_form = document.querySelector("iframe.utterances-frame");
+  if (body != null) {
+    if (body.classList.contains("dark")) {
+      body.classList.replace("dark", "light");
+      if (comment_form != null) {
+        comment_form.contentWindow.postMessage(
+          { type: "set-theme", theme: "github-light" },
+          "https://utteranc.es/"
+        )
+      }
+    } else {
+      body.classList.remove("light");
+      body.classList.add("dark");
+      if (comment_form != null) {
+        comment_form.contentWindow.postMessage(
+          { type: "set-theme", theme: "github-dark" },
+          "https://utteranc.es/"
+        )
+      }
+    }
+    console.log(body)
+  }
+}

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>