Bootstrap输入框组

    <link rel="stylesheet" href="http://cdn.static.runoob.com/libs/bootstrap/3.3.7/css/bootstrap.min.css">  
    <script src="http://cdn.static.runoob.com/libs/jquery/2.1.1/jquery.min.js"></script>
    <script src="http://cdn.static.runoob.com/libs/bootstrap/3.3.7/js/bootstrap.min.js"></script>




<div style="padding: 100px 100px 10px;">
    <form>
        <div class="input-group">
            <span class="input-group-addon">@</span>
            <input type="text" class="form-control" placeholder="twitterhandle">
        </div>
    </form>
</div>