box2.html

<!DOCTYPE html>
<html lang="en">
<head>
<title>CSS</title>
<meta charset="utf-8">
<style>
.div1 {width: 200px;
       height: 200px;
       background-color: #D1ECFF;
       border: 3px dashed #000000;
       padding: 5px;
}
.div2 {width: 100px;
       height: 100px;
       background-color: #ffffff;
       border: 3px ridge #000000;
       padding: 5px;
       margin: 10px;
}
</style>
</head>
<body>
<div class="div1">
  This is the outer box.
  <div class="div2">
  This is the inner box.
  </div>
</div>
</body>
</html>