html - 如何为元素设置边框？

Question

为什么下面的边框不显示tbody？我试过rules="groups"了，边框出现了，但只在两个tbody部分之间，它被折叠了。

table.sectioned tbody {
  border: 2px solid black;
  border-collapse: separate;
  border-spacing: 4px;
}

<table class="sectioned">
  <tbody>
    <tr><td colspan="2"><b>General Data</b></td></tr>
    <tr><td>Tail Number</td><td>N0809021</td></tr>
    <tr><td>Type of Ownership</td><td>personal</td></tr>
    <tr><td>Type of Aircraft</td><td>aircraft under 13,000 pounds</td></tr>
    <tr><td>Year of Manufacture</td><td>1999</td></tr>
    <tr><td>Use of Aircraft</td><td>private</td></tr>
    <tr><td>Start Date</td><td></td></tr>
    <tr><td>Policy Length</td><td>6 months</td></tr>
  </tbody>
  <tbody>
    <tr><td colspan="2"><b>Additional Aircraft Information</b></td></tr>
    <tr><td>Manufacturer</td><td></td></tr>
    <tr><td>Model</td><td></td></tr>
    <tr><td>Engine Make</td><td></td></tr>
    <tr><td>Number of Seats</td><td></td></tr>
  </tbody>
</table>

Answer 1

添加：

table {border-collapse: collapse;}

小提琴

Answer 2

将 display:block 添加到您的 tbody 样式中。尝试这个

tbody{
    display:block;
    border: 2px solid black;
    border-collapse: separate;
    border-spacing: 4px; 
}

你可以在这个小提琴上测试它

Answer 3

使用box-shadow而不是border. 无论border-collapse应用哪个值，它都有效。此外，您也可以申请border-radius。

tbody {
  box-shadow: 0 0 0 1px black;
  border-radius: 5px;
}

<table>
  <thead>
    <tr>
      <th>Firstname</th>
      <th>Lastname</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Jill</td>
      <td>Smith</td>
    </tr>
    <tr>
      <td>Eve</td>
      <td>Jackson</td>
    </tr>
  </tbody>
</table>

Answer 4

.table_body, .tbody_td, .tbody_th 
{ border: 1px solid black; }
.table_body  { border-collapse: collapse; }
<table>
<thead> 
<tr>
<th>Firstname</th>
<th>Lastname</th>
</tr>
</thead>
<tbody class="table_body">
<tr>
<td class="tbody_td">Jill</td>
<td class="tbody_td">Smith</td>
</tr>
<tr>
<td class="tbody_td">Eve</td>
<td class="tbody_td">Jackson</td>
</tr>
</tbody>
</table>