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<html><title>W3.CSS</title><meta name="viewport" content="width=device-width, initial-scale=1"><link rel="stylesheet" href="4/w3.css"><body><div class="w3-sidebar w3-bar-block w3-light-grey w3-card" style="width:130px"> <h5 class="w3-bar-item">Menu</h5> <button class="w3-bar-item w3-button tablink" onclick="openCity(event, 'London')">London</button> <button class="w3-bar-item w3-button tablink" onclick="openCity(event, 'Paris')">Paris</button> <button class="w3-bar-item w3-button tablink" onclick="openCity(event, 'Tokyo')">Tokyo</button></div><div style="margin-left:130px"> <div class="w3-padding">Vertical Tab Example (sidebar)</div> <div id="London" class="w3-container city" style="display:none"> <h2>London</h2> <p>London is the capital city of England.</p> <p>It is the most populous city in the United Kingdom, with a metropolitan area of over 13 million inhabitants.</p> </div> <div id="Paris" class="w3-container city" style="display:none"> <h2>Paris</h2> <p>Paris is the capital of France.</p> <p>The Paris area is one of the largest population centers in Europe, with more than 12 million inhabitants.</p> </div> <div id="Tokyo" class="w3-container city" style="display:none"> <h2>Tokyo</h2> <p>Tokyo is the capital of Japan.</p> <p>It is the center of the Greater Tokyo Area, and the most populous metropolitan area in the world.</p> </div></div><script>function openCity(evt, cityName) { var i, x, tablinks; x = document.getElementsByClassName("city"); for (i = 0; i < x.length; i++) {