{% capture excerpt %}
  {{ post.excerpt | replace: "<p>", "" | replace: "</p>", "" }}
{% endcapture %}

{% assign excerpt_length = excerpt | size %}

<em class="post-link__excerpt">
  {% if excerpt_length > 140 %}
    {{ excerpt | truncatewords: 20, '…' }}
  {% else %}
    {{ excerpt }}
  {% endif %}
</em>