1.、首先将html和body设置为width:100%和height:100%;然后将父容器div宽高设置为100%即可实现div满屏
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
*{
margin: 0;
padding: 0;
}
html,body{
height: 100%;
width: 100%;
}
.test{
height: 100%;
/* height:9.03rem; */
width: 100%;
border: 1px solid red;
}
.child{
height:2rem;
width:100%;
border: 1px solid pink;
}
</style>
<script src="./flexible.js"></script>
</head>
<body>
<div class="test">
<div class="child"></div>
</div>
</body>
</html>