<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>bootstrap栅格系统</title><link rel="stylesheet" href="./bootstrap.min.css">
</head>
<body><!-- 视口宽度大于等于1200px,一行排4个盒子 --><!-- 视口宽度大于等于768px,一行排2个盒子 --><!-- 视口宽度大于等于576px,一行排1个盒子 --><!-- 嵌套结构: 版心，row，子级 --><div class="container"><div class="row"><div class="col-xl-3">1</div><div class="col-xl-3">2</div><div class="col-xl-3">3</div><div class="col-xl-3">4</div></div></div><br><br><div class="container"><div class="row"><div class="col-md-6">1</div><div class="col-md-6">2</div><div class="col-md-6">3</div><div class="col-md-6">4</div></div></div><br><br><div class="container"><div class="row"><div class="col-sm-12">1</div><div class="col-sm-12">2</div><div class="col-sm-12">3</div><div class="col-sm-12">4</div></div></div>
</body>
</html>
