Submissions tab html broken

We have a simple form with table and check boxes, something like

<form>
  <label>
    Name
    <input type="text" name="name" required>
  </label>

  <label>
    Email
    <input type="email" name="email" required>
  </label>

  <label>
    Message
    <textarea name="message" rows="5"></textarea>
  </label>

  <p>Available study times:</p>

  <table>
    <thead>
      <tr>
        <th>Time</th>
        <th>Mon</th>
        <th>Tue</th>
        <th>Wed</th>
        <th>Thu</th>
        <th>Fri</th>
        <th>Sat</th>
        <th>Sun</th>
      </tr>
    </thead>

    <tbody>
      <tr>
        <th>Morning</th>
        <td><input type="checkbox" name="morning_mon"></td>
        <td><input type="checkbox" name="morning_tue"></td>
        <td><input type="checkbox" name="morning_wed"></td>
        <td><input type="checkbox" name="morning_thu"></td>
        <td><input type="checkbox" name="morning_fri"></td>
        <td><input type="checkbox" name="morning_sat"></td>
        <td><input type="checkbox" name="morning_sun"></td>
      </tr>

      <tr>
        <th>Afternoon</th>
        <td><input type="checkbox" name="afternoon_mon"></td>
        <td><input type="checkbox" name="afternoon_tue"></td>
        <td><input type="checkbox" name="afternoon_wed"></td>
        <td><input type="checkbox" name="afternoon_thu"></td>
        <td><input type="checkbox" name="afternoon_fri"></td>
        <td><input type="checkbox" name="afternoon_sat"></td>
        <td><input type="checkbox" name="afternoon_sun"></td>
      </tr>

      <tr>
        <th>Evening</th>
        <td><input type="checkbox" name="evening_mon"></td>
        <td><input type="checkbox" name="evening_tue"></td>
        <td><input type="checkbox" name="evening_wed"></td>
        <td><input type="checkbox" name="evening_thu"></td>
        <td><input type="checkbox" name="evening_fri"></td>
        <td><input type="checkbox" name="evening_sat"></td>
        <td><input type="checkbox" name="evening_sun"></td>
      </tr>
    </tbody>
  </table>

  <button type="submit">Send</button>
</form>

in the Submissions tab it breaks the display