onders.org_zola_theme/templates/shortcodes/gallery.html

<div class="gallery">
  {% for path in images %}
  {% if section %}
  {% set full_path = section.path ~ path %}
  {% endif %}
  {% if page %}
  {% set full_path = page.path ~ path %}
  {% endif %}
  {% set thumb = resize_image(path=full_path, width=120, height=120) %}
  <a href="#{{ loop.index }}"><img class="thumbnail" src="{{ thumb.url }}"></a>

  <div class="lightbox" id="{{ loop.index }}">
    {% if loop.first and loop.last %}
    <a href="#" class="close full">
      <div class="image">
          <img src="{{ path }}">
      </div>
    </a>
    {% else %}
    <a href="#"><span class="close"></span></a>
    {% if loop.first %}
    <a href="#{{ images | length }}"><span class="prev end"></span></a>
    {% else %}
    <a href="#{{ loop.index - 1 }}"><span class="prev"></span></a>
    {% endif %}
    {% if loop.last %}
    <a href="#1"><span class="next start"></span></a>
    {% else %}
    <a href="#{{ loop.index + 1 }}"><span class="next"></span></a>
    {% endif %}
    <div class="image">
      <img src="{{ path }}">
    </div>
    {% endif %}
  </div>
  {% endfor %}
</div>