CSS에서 \'display: table-column\'은 어떻게 작동하나요?

<code class="html"><table>
  <col></col>
  <col></col>
  <tr>
    <td></td>
    <td></td>
  </tr>
  <tr>
    <td></td>
    <td></td>
  </tr>
</table></code>

<code class="css">.mytable {
  display: table;
}

.myrow {
  display: table-row;
}

.mycell {
  display: table-cell;
}

.column1 {
  display: table-column;
  background-color: green;
}

.column2 {
  display: table-column;
}</code>

<code class="html"><div class="mytable">
  <div class="column1"></div>
  <div class="column2"></div>
  <div class="myrow">
    <div class="mycell">contents of first cell in row 1</div>
    <div class="mycell">contents of second cell in row 1</div>
  </div>
  <div class="myrow">
    <div class="mycell">contents of first cell in row 2</div>
    <div class="mycell">contents of second cell in row 2</div>
  </div>
</div></code>