<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
*{
margin:0;
padding:0;
}
body,html{
height:100%;
}
.left{
200px;
height:80%;
background:red;
float:left;
}
.right{
height:100%;
background:orange;
/* 触发BFC */
overflow:hidden;
}
</style>
</head>
<body>
<div class="left"></div>
<div class="right"></div>
</body>
</html>