<!DOCTYPE html>

<html>
<head>
  <style type="text/css" media="screen">
    body {
      height: 1000px;
      margin: 0;
    }
    
    .box {
        height: 100px;
        width: 100px;
        margin: 100px 0;
        background-color: green;
    }
  </style>
</head>
<body>

    <div class="box">
    </div>
    
</body>
</html>