<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style>
#div1{height:200px;border:1px solid red;}
#div2{width:50%;height:200px;background:#ccc;}
</style>
</head>
<body>
<div id="div1">
<div id="div2"></div>
</div>
</body>
</html>
