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<!DOCTYPE html>
<html>
<title>W3.CSS</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="../lib/w3.css">
<body>

<button class="w3-btn" onclick="document.getElementById('id01').style.display='block'">Show container</button> 

<div id="id01" class="w3-container w3-red" style="display:none">
  <span onclick="this.parentElement.style.display='none'" class="w3-closebtn">x</span>
  <p>London is the capital city of England.</p>
</div>

</body>
</html>