<div class="treetable d-flex w-100">

  <table class="table">

    <thead>

      <tr>

        <th scope="col">A</th>

        <th scope="col">B</th>

        <th scope="col">C</th>

      </tr>

    </thead>

    <tbody>

      <tr data-depth="1">

        <td>Thing with children</td>

        <td>100</td>

        <td>200</td>

      </tr>

      <tr>

        <td>Child 1</td>

        <td>300</td>

        <td>400</td>

      </tr>

      <tr>

        <td>Child 2</td>

        <td>500</td>

        <td>600</td>

      </tr>

      <tr data-depth="1">

        <td>Thing with no children</td>

        <td>700</td>

        <td>800</td>

      </tr>

    </tbody>

  </table>

</div>