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        <meta charset="utf-8"> 
        <title>菜鸟教程(runoob.com)</title> 
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        <div class="container">
            <h2>实例</h2>
            <p> .close 类可以显示一个关闭按钮。</p>
            <button type="button" class="close"><span aria-hidden="true">x</span><span class="sr-only">关闭</span></button>
        </div>

    </body>
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