Fixed image lazy loading.

_layouts/post.html

@@ -64,13 +64,19 @@ layout: default
       </div> <!-- .post-meta -->
 
       <div class="post-content">
-
         {% if page.image %}
           <img src="{{ page.image }}">
         {% endif %}
-
-        {{ content }}
-
+        <!-- Add lozad class into image tags. see: <https://github.com/ApoorvSaxena/lozad.js#usage> -->
+        {% if content contains '<img src=' %}
+          {% capture loading %}
+           {{ "/assets/img/commons/loading.png" | relative_url }}
+          {% endcapture %}
+          {% assign replacement = '<img src=' | append: loading | append: ' data-src=' %}
+          {{ content | replace: '<img src=', replacement }}
+        {% else %}
+          {{ content }}
+        {% endif %}
       </div>
 
       <div class="post-tail-wrapper text-muted">