Use <article> and <aside>

_layouts/page.html

@@ -2,7 +2,7 @@
 layout: default
 ---
 
-<div class="page">
+<article class="page">
   <h1 class="page-title">{{ page.title }}</h1>
   {{ content }}
-</div>
+</article>

_layouts/post.html

@@ -2,13 +2,13 @@
 layout: default
 ---
 
-<div class="post">
+<article class="post">
   <h1 class="post-title">{{ page.title }}</h1>
   <span class="post-date">{{ page.date | date_to_string }}</span>
   {{ content }}
-</div>
+</article>
 
-<div class="related">
+<aside class="related">
   <h2>Related Posts</h2>
   <ul class="related-posts">
     {% for post in site.related_posts limit:3 %}
@@ -22,4 +22,4 @@ layout: default
       </li>
     {% endfor %}
   </ul>
-</div>
+</aside>

index.html

@@ -5,7 +5,7 @@ title: Home
 
 <div class="posts">
   {% for post in paginator.posts %}
-  <div class="post">
+  <article class="post">
     <h1 class="post-title">
       <a href="{{ post.url }}">
         {{ post.title }}
@@ -15,7 +15,7 @@ title: Home
     <span class="post-date">{{ post.date | date_to_string }}</span>
 
     {{ post.content }}
-  </div>
+  </article>
   {% endfor %}
 </div>