<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>getBoundingClientRect</title>
<link rel="stylesheet" href="css/reset.min.css">
<style>
html,
body {
height: 300%;
background: -webkit-linear-gradient(top left, pink, orange);
}
#box {
position: absolute;
left: 200px;
top: 800px;
width: 100px;
height: 100px;
background: red;
}
</style>
</head>
<body>
<div id="box"></div>
<script>
let box = document.querySelector('#box');
</script>
</body>
</html>