在一個表格內嵌套另一個表格時，如何居中？

在一個表格內嵌套另一個表格時，如何居中？

假設大表格為：

<table id="tableRow">
  <tr>
    <th>City</th>
    <th>Date</th>
    <th>Temperature</th>
    <th>Altitude</th>
    <th>Population</th>
    <th>Diner Rating</th>
  </tr>
  <tr>
    <td>Walla Walla, WA</td>
    <td class="center">June 15th</td>
    <td class="center">75</td>
    <td>1,204 ft</td>
    <td>29,686</td>
    <td class="center">4/5</td>
  </tr>
  <tr class="cellcolor">
    <td>Magic City, ID</td>
    <td class="center">June 25th</td>
    <td class="center">74</td>
    <td class="">5,312 ft</td>
    <td>50</td>
    <td class="center">3/5</td>
  </tr>
  <tr>
    <td>Bountiful, UT</td>
    <td class="center"> July 10th</td>
    <td class="center">91</td>
    <td>4,226 ft</td>
    <td>41,173</td>
    <td class="center">4/5</td>
  </tr>
  <tr class="cellcolor">
    <td>Last Chance, CO</td>
    <td class="center">July 23rd</td>
    <td class="center">102</td>
    <td>4,780 ft</td>
    <td>265</td>
    <td class="center">3/5</td>
  </tr>
  <tr>
    <td rowspan="2">Truth or Consequences, NM</td>
    <td class="center">August 9th</td>
    <td class="center">93</td>
    <td rowspan="2">4,242 ft</td>
    <td rowspan="2">7,289</td>
    <td class="center">5/5</td>
  </tr>
  <tr>
    <td class="center">August 27th</td>
    <td class="center">98</td>
    <td class="center">
      <table>
        <tr>
          <th>Tess</th>
          <td>5/5</td>
        </tr>
        <tr>
          <th>Tony</th>
          <td>4/5</td>
        </tr>
      </table>
    </td>
  </tr>
  <tr class="cellcolor">
    <td>Why, AZ</td>
    <td class="center">August 18th</td>
    <td class="center">104</td>
    <td>860 ft</td>
    <td>480</td>
    <td class="center">3/5</td>
  </tr>
</table>

小表格為：

      <table>
        <tr>
          <th>Tess</th>
          <td>5/5</td>
        </tr>
        <tr>
          <th>Tony</th>
          <td>4/5</td>
        </tr>
      </table>

使其居中的CSS為：

table table
{
  margin-left:      20px;
  margin-right:     20px;
}

效果：

綜上，在一個表格內嵌套另一個表格時，居中的一種方法為設置小表格的外邊距。