<html><head> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css"> <script src="https://libs.baidu.com/jquery/2.1.4/jquery.min.js"></script> <script src="https://apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script></head><body><div class="container"> <h2>Example</h2> <p>The .sr-only class hides an element to all devices except screen readers:</p> <a class="sr-only" href="#">Skip to main content</a> <p>Combine .sr-only with .sr-only-focusable to show the element again when it is focused (e.g. by a keyboard-only user):</p> <a class="sr-only sr-only-focusable" href="#">Skip to main content</a></div></body></html>