fix headline level numbering

index.html

@@ -5,7 +5,7 @@ layout: default
 {% for post in site.posts %}
 	<article class="feed-item">
 		<small class="date">{{ post.date | date: "%Y-%m-%d" }}</small>
-		<h3><a href="{{ post.url }}">{{ post.title }}</a></h3>
+		<h2><a href="{{ post.url }}">{{ post.title }}</a></h2>
 		{{ post.excerpt }}
 	</article>
 {% endfor %}