:first-child

Baseline Widely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

* Some parts of this feature may have varying levels of support.

:first-child CSS 伪类表示在一组兄弟元素中的第一个元素。

尝试一下

p {
  font-weight: bold;
}

li:first-child {
  border: 2px solid orange;
}

<p>Track &amp; field champions:</p>
<ul>
  <li>Adhemar da Silva</li>
  <li>Wang Junxia</li>
  <li>Wilma Rudolph</li>
  <li>Babe Didrikson-Zaharias</li>
  <li>Betty Cuthbert</li>
  <li>Fanny Blankers-Koen</li>
  <li>Florence Griffith-Joyner</li>
  <li>Irena Szewinska</li>
  <li>Jackie Joyner-Kersee</li>
  <li>Shirley Strickland</li>
  <li>Carl Lewis</li>
  <li>Emil Zatopek</li>
  <li>Haile Gebrselassie</li>
  <li>Jesse Owens</li>
  <li>Jim Thorpe</li>
  <li>Paavo Nurmi</li>
  <li>Sergei Bubka</li>
  <li>Usain Bolt</li>
</ul>

语法

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

示例

基础示例

HTML

html
<div>
  <p>此文本已选中！</p>
  <p>此文本未选中。</p>
</div>

<div>
  <h2>此文本未被选中：它不是一个 `p`。</h2>
  <p>此文本未被选中。</p>
</div>

CSS

css
p:first-child {
  color: lime;
  background-color: black;
  padding: 5px;
}

结果

样式化列表

HTML

html
<ul>
  <li>Item 1</li>
  <li>Item 2</li>
  <li>
    Item 3
    <ul>
      <li>Item 3.1</li>
      <li>Item 3.2</li>
      <li>Item 3.3</li>
    </ul>
  </li>
</ul>

CSS

css
ul li {
  color: blue;
}

ul li:first-child {
  color: red;
  font-weight: bold;
}

结果

规范

Specification
Selectors Level 4
# first-child-pseudo

浏览器兼容性

BCD tables only load in the browser

参见