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<html><title>W3.CSS</title><meta name="viewport" content="width=device-width, initial-scale=1"><link rel="stylesheet" href="https://www.w3schools.com/w3css/5/w3.css"><body><div class="w3-container"> <h2>Toggle Show/Hide</h2> <p>Click on the button to show/hide a paragraph.</p> <button onclick="myFunction()" class="w3-button w3-black">Button</button> <p>Paragraph 1.</p> <p id="Demo" class="w3-hide">Paragraph 2.</p> <p>Paragraph 3.</p></div><script>function myFunction() { var x = document.getElementById("Demo"); if (x.className.indexOf("w3-show") == -1) { x.className += " w3-show"; } else { x.className = x.className.replace(" w3-show", ""); }}</script></body></html>