console
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程(runoob.com)</title>
<style>
*{
margin: 0;
padding: 0
}
ul{
list-style: none
}
.box{
display: flex;
width: 500px;
height: 400px;
flex-wrap: wrap;
justify-content: space-around;
align-content: space-around;
border: 1px solid #ccc
}
.box li{
width: 150px;
height: 150px;
border: 1px solid red;
}
</style>
</head>
<body>
<div id="main">
<ul class="box">
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
</ul>
</div>
</body>
</html>