html中跨行或跨列的表格单元格设置

<table class="my-table" border="1">
  <tr>
    <td rowspan="2" colspan="2">等级1</td>
    <td colspan="3">等级2</td>
  </tr>
  <tr>
    <td>低</td>
    <td>中</td>
    <td>高</td>
  </tr>
  <tr>
    <td rowspan="4">安全影响级别</td>
  </tr>
  <tr>
    <td>特别严重</td>
    <td>中</td>
    <td>高</td>
    <td>极高</td>
  </tr>
  <tr>
    <td>严重</td>
    <td>低</td>
    <td>中</td>
    <td>极高</td>
  </tr>
  <tr>
    <td>一般</td>
    <td>低</td>
    <td>低</td>
    <td>高</td>
  </tr>
</table>

.my-table{
  width: 100%;
  border: 1px solid #ccc!important;
  border-collapse: collapse;
  border-spacing: 0;
  tr{
    padding: 8px 20px;
    border: 1px solid #ccc !important;
  }
  td{
    padding: 8px 20px;
    border: 1px solid #ccc !important;
  }
}

显示结果