<div class="with-js">
  <fieldset class="sample-field">
    <legend>Samples</legend>
    <div class="key-container"></div>
  </fieldset>
  <fieldset>
    <legend>Panel</legend>
    <input type="checkbox" name="loop" class="loop" id="loop">
    <label for="loop" class="checkbox--label">Loop</label>
  </fieldset>
</div>