awebsite/templates/shortcodes/gallery.html

{% set gallery_data = load_data(literal = body, format="json") %}

<div id="image-gallery">
  <ul class="gallery">
    {% for item in gallery_data %}
      <li class="gallery-item">
        <a href="{{ item.file }}" class="lightbox" target="_blank">
          <img src="{{ item.file }}" {% if item.alt %}alt="{{ item.alt }}"{% endif %}>
        </a>
        {% if item.title %}
          <p class="caption">{{ item.title }}</p>
        {% endif %}
      </li>
    {% endfor %}
  </ul>
</div>