first-child 选中第一个标签 应用CSS样式
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Title</title>
<style type="text/css">
/* 选中第一个标签 */
.box ul li:first-child{
color: red;
}
</style>
</head>
<body>
<div class="box">
<ul>
<li class="item1">
1
<a href="#">jack</a>
</li>
<li class="item2">
2
<a href="#">ben</a>
</li>
<li class="item3">
3
<a href="#">peter</a>
</li>
</ul>
</div>
</body>
</html>
last-child 选中最后一个标签 应用CSS样式
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Title</title>
<style type="text/css">
/* 选中最后一个标签 */
.box ul li:last-child{
color: red;
}
</style>
</head>
<body>
<div class="box">
<ul>
<li class="item1">
1
<a href="#">jack</a>
</li>
<li class="item2">
2
<a href="#">ben</a>
</li>
<li class="item3">
3
<a href="#">peter</a>
</li>
</ul>
</div>
</body>
</html>
nth-child() 选中当前指定的标签，数值从1开始
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Title</title>
<style type="text/css">
/* 选中当前指定的标签，数值从1开始 */
.box ul li:nth-child(2){
color: red;
font-size:30px;
}
</style>
</head>
<body>
<div class="box">
<ul>
<li class="item1">
1
<a href="#">jack</a>
</li>
<li class="item2">
2
<a href="#">ben</a>
</li>
<li class="item3">
3
<a href="#">peter</a>
</li>
</ul>
</div>
</body>
</html>
选中第二个标签
nth-child(n)
n表示选中所有 从0开始的 0的时候表示没有选中
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Title</title>
<style type="text/css">
/* n表示选中所有 从0开始的 0的时候表示没有选中 */
.box ul li:nth-child(n){
color: red;
font-size:30px;
}
</style>
</head>
<body>
<div class="box">
<ul>
<li class="item1">
1
<a href="#">jack</a>
</li>
<li class="item2">
2
<a href="#">ben</a>
</li>
<li class="item3">
3
<a href="#">peter</a>
</li>
</ul>
</div>
</body>
</html>
nth-child(2n) 偶数
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Title</title>
<style type="text/css">
/* 偶数 */
.box ul li:nth-child(2n){
color: red;
font-size:30px;
}
</style>
</head>
<body>
<div class="box">
<ul>
<li class="item1">
1
<a href="#">jack</a>
</li>
<li class="item2">
2
<a href="#">ben</a>
</li>
<li class="item3">
3
<a href="#">peter</a>
</li>
<li class="item4">
4
<a href="#">mike</a>
</li>
<li class="item5">
5
<a href="#">tom</a>
</li>
</ul>
</div>
</body>
</html>
nth-child(2n-1) 奇数
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Title</title>
<style type="text/css">
/* 奇数 */
.box ul li:nth-child(2n-1){
color: red;
font-size:30px;
}
</style>
</head>
<body>
<div class="box">
<ul>
<li class="item1">
1
<a href="#">jack</a>
</li>
<li class="item2">
2
<a href="#">ben</a>
</li>
<li class="item3">
3
<a href="#">peter</a>
</li>
<li class="item4">
4
<a href="#">mike</a>
</li>
<li class="item5">
5
<a href="#">tom</a>
</li>
</ul>
</div>
</body>
</html>
隔几换色，隔行换色
隔3换色，就是4n+1，隔4换色，就是5n+1。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Title</title>
<style type="text/css">
/* 奇数 */
.box ul li:nth-child(4n+1){
color: red;
font-size:30px;
}
</style>
</head>
<body>
<div class="box">
<ul>
<li class="item1">
1
<a href="#">jack</a>
</li>
<li class="item2">
2
<a href="#">ben</a>
</li>
<li class="item3">
3
<a href="#">peter</a>
</li>
<li class="item4">
4
<a href="#">mike</a>
</li>
<li class="item5">
5
<a href="#">tom</a>
</li>
<li class="item6">
6
<a href="#">ken</a>
</li>
<li class="item7">
7
<a href="#">mary</a>
</li>
<li class="item8">
8
<a href="#">tony</a>
</li>
<li class="item9">
9
<a href="#">Howard</a>
</li>
</ul>
</div>
</body>
</html>