docs/_includes/post_details.html

{% if post %}
  {% assign author        = post.data.author %}
  {% assign post_date     = post.date %}
  {% assign modified_date = post.modified_date %}
  {% assign url           = post.url %}
{% else %}
  {% assign post_date     = page.date %}
{% endif %}

{% assign post_author = author %}
{% assign post_gravatar = '' %}

{% for a in authors %}
  {% if a.name == author %}
    {% if a.twitter %}
      {% capture post_author %}<a href="https://twitter.com/{{a.twitter}}">{{ author }}</a>{% endcapture %}
    {% endif %}
    {% if a.gravatar %}
      {% capture post_gravatar %}https://gravatar.com/avatar/{{ a.gravatar }}{% endcapture %}
    {% endif %}
  {% endif %}
{% endfor %}

{% if modified_date %}
  {% capture modified_date %}<strong>Updated:</strong> {{ modified_date | date_to_long_string }}<br>{% endcapture %}
{% endif %}

<div class="post">
  <div class="media">
    <a class="pull-left" href="#">
    <img class="media-object img-circle img-responsive" src='{{ post_gravatar }}' alt='{{ author }}'>
    </a>
    <div class="media-body">
    <p>
      <strong>By:</strong> {{ post_author }}<br>
      <strong>Published:</strong> {{ post_date | date_to_long_string }}<br>
      {% if page.url == "/blog/" or page.url contains "/blog/page" or page.url == "/" %}
        {% if post.page.excerpt %}
          {{ post.page.excerpt | liquid | markdown | strip_html | truncatewords: 30, '' }}
        {% else %}
          {{ post.content | first_paragraph | strip_html | truncatewords: 30, '' }}
        {% endif %}<a href='{{ site.baseurl }}{{ url }}'>[...]</a>
      {% endif %}
    </p>
    </div>
  </div>
</div>