webbed-site/templates/shortcodes/gallery.html

<div style="text-align: center;">
{% for asset in page.assets -%}
  {%- if asset is matching("[.](jpg|png|gif)$") -%}
    {% set image = resize_image(path=asset, width=350, height=350) %}
    <a href="{{ get_url(path=asset) }}" target="_blank">
      <img src="{{ image.url }}">
    </a>
  {%- endif %}
{%- endfor %}
</div>