feat: add side toc support and update toc style

templates/partials/side_toc.html

@@ -0,0 +1,23 @@
+{% if page.toc and page.extra.side_toc | default(value=config.extra.side_toc) %}
+<nav
+  class="prose prose-neutral dark:prose-invert prose-a:block prose-a:truncate prose-a:font-normal prose-a:secondary-link max-h-lvh overflow-y-auto px-2 pt-18 pb-4"
+>
+  <b class="ml-1.5">Table of Contents</b>
+  <ul>
+    {% for h1 in page.toc %}
+    <li>
+      <a href="#{{ h1.id | safe }}">{{ h1.title }}</a>
+      {% if h1.children %}
+      <ul>
+        {% for h2 in h1.children %}
+        <li>
+          <a href="#{{ h2.id | safe }}">{{ h2.title }}</a>
+        </li>
+        {% endfor %}
+      </ul>
+      {% endif %}
+    </li>
+    {% endfor %}
+  </ul>
+</nav>
+{% endif %}