<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Domintro</title>
</head>
<style>
  .large {
    font-size: 48px;    
  }
  .center {
    text-align: center;
  }
</style>
<body>
<div class="large center">
  Hello Duck Land
</div>
<p>
  This is a nice duck
  <img src="http://www.saintpetersblog.com/wp-content/uploads/2014/08/rubber-duck.jpg" width=300 />
  <button>Click here to hide/show it</button>
</p>

</body>
</html>

External CSS

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External JavaScript

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