Tab change automatically with the button index click

<pre data-line=""> <code readonly="true"> <xmp> <a>Button</a> <a>Button</a> <a>Button</a> <a>Button</a> <a>Button</a> <a>Button</a> tab content tab content tab content tab content tab content tab content <style> .btn { border: 1px solid; padding: 10px; } .btn.selected { background: red; } .tab { background: #ccc; padding: 100px; opacity: 0.5; } .tab.selected { opacity: 1; } </style></xmp> </code> </pre> <a>Button</a> <a>Button</a> <a>Button</a> <a>Button</a> <a>Button</a> <a>Button</a> tab content tab content tab content tab content tab content tab content <style> .btn { border: 1px solid; padding: 10px; } .btn.selected { background: red; } .tab { background: #ccc; padding: 100px; opacity: 0.5; } .tab.selected { opacity: 1; } </style>