<div class="mentoring-table {{ self.type }}" style="background-image: url({{ bg_image_url }})">
  <table>
    {% if header_frags %}
    <thead>
      {% for name, c in header_frags %}
      {{c.body_html|safe}}
      {% endfor %}
    </thead>
    {% endif %}
    <tr>
      {% for name, c in columns_frags %}
      {{c.body_html|safe}}
      {% endfor %}
    </tr>
  </table>
</div>

<div class="mentoring-table {{ self.type }}" style="background-image: url({{ bg_image_url }})">
  <table>
    {% if header_frags %}
    <thead>
      {% for name, c in header_frags %}
      {{c.body_html|safe}}
      {% endfor %}
    </thead>
    {% endif %}
    <tbody>
      <tr>
        {% for name, c in columns_frags %}
        {{c.body_html|safe}}
        {% endfor %}
      </tr>
    </tbody>
  </table>
</div>

Add <tbody> to mentoring tables
html-css-review: Add <tbody> to mentoring tables
