Correct headline hierarchy

_pages/year-archive.html

@@ -10,7 +10,7 @@ author_profile: false
 {% for post in site.posts %}
   {% capture year %}{{ post.date | date: '%Y' }}{% endcapture %}
   {% if year != written_year %}
-    <h3>{{ year }}</h3>
+    <h2>{{ year }}</h2>
     {% capture written_year %}{{ year }}{% endcapture %}
   {% endif %}
   {% include archive-list-single %}