Fixed some HTML tags.

_includes/panel.html

@@ -21,7 +21,7 @@
   {% endfor %}
 
   {% if lastmod_list.size > 0 %}
-    <div id="access-lastmod" class="post mb-4"">
+    <div id="access-lastmod" class="post mb-4">
       <h3 data-toc-skip>
         {{- site.data.label.panel.lastmod -}}
       </h3>

_includes/related-posts.html

@@ -56,7 +56,7 @@
             </span>
             <h3 class="pt-0 mt-2 mb-3" data-toc-skip>{{ post.title }}</h3>
             <div class="text-muted small">
-              <p>{{ post.content | markdownify | strip_html | truncate: 200 }}</p>
+              <p>{{ post.content | markdownify | strip_html | truncate: 200 | replace: '&', '&amp;' }}</p>
             </div>
           </div>
         </a>

_includes/sidebar.html

@@ -12,7 +12,7 @@
         {% if avatar | slice: 0 == '/' %}
           {% assign avatar = avatar | prepend: site.baseurl %}
         {% endif %}
-        <img src="{{ avatar }}"></img>
+        <img src="{{ avatar }}">
       </a>
     </div>