CodePen

HTML

            
              <!DOCTYPE>
<html>
<head>
<title>What About This?</title>

<style>
html {background:#39F; height:100%; padding:1%; box-sizing: border-box; }
body {background:#fff; margin:0; padding:0; height:100%; border-radius:15px; }
</style>

</head>

<body>
</body>
</html>

            
          
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CSS

            
              
            
          
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JS

            
              
            
          
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