flex/templates/partial/neighbors.html

{% if PLUGINS and ('neighbors' in PLUGINS or 'pelican.plugins.neighbors' in PLUGINS) %}
  <div class="neighbors">
  {% if article.prev_article %}
    <a class="btn float-left" href="{{ SITEURL }}/{{ article.prev_article.url }}" title="{{ article.prev_article.title|striptags }}">
      <i class="fa fa-angle-left"></i> {{ _('Previous Post') }}
    </a>
  {% endif %}
  {% if article.next_article %}
    <a class="btn float-right" href="{{ SITEURL }}/{{ article.next_article.url }}" title="{{ article.next_article.title|striptags }}">
      {{ _('Next Post') }} <i class="fa fa-angle-right"></i>
    </a>
  {% endif %}
  </div>
{% endif %}