:only-child

**:only-child** CSS 伪类 表示没有兄弟节点的元素。 这与 :first-child:last-child 或 :nth-child(1):nth-last-child(1) 相同，但具有更低的特异性。

试一试

语法

css
:only-child {
  /* ... */
}

示例

基本示例

HTML

html
<div>
  <div>I am an only child.</div>
</div>

<div>
  <div>I am the 1st sibling.</div>
  <div>I am the 2nd sibling.</div>
  <div>
    I am the 3rd sibling,
    <div>but this is an only child.</div>
  </div>
</div>

CSS

css
div:only-child {
  color: red;
}

div {
  display: inline-block;
  margin: 6px;
  outline: 1px solid;
}

结果

列表示例

HTML

html
<ol>
  <li>
    First
    <ul>
      <li>This list has just one element.</li>
    </ul>
  </li>
  <li>
    Second
    <ul>
      <li>This list has three elements.</li>
      <li>This list has three elements.</li>
      <li>This list has three elements.</li>
    </ul>
  </li>
</ol>

CSS

css
li li {
  list-style-type: disc;
}

li:only-child {
  color: red;
  list-style-type: square;
}

结果

规范

规范
选择器级别 4
# only-child-pseudo

浏览器兼容性

BCD 表格仅在浏览器中加载

另请参阅