{% if site.categories.size != 0 %}
  {% for category in site.categories %}
    <h1><a class="category" href="{{ '/categories/' | relative_url }}{{ category[0] | slugify: 'pretty' }}">{{ category[0] }}</a></h1>
    <hr/>
    <ul>
      {% for post in category[1] %}
        <li><a href="{{ post.url | relative_url }}">{{ post.date | date: "%Y-%m-%d" }} &mdash; {{ post.title }}</a></li>
      {% endfor %}
    </ul>
  {% endfor %}
{% else %}
  <p>Sorry, no posts have been added yet.</p>
  <hr/>
{% endif %}