html - Bootstrap CSS glyphicon 不显示。我应该怎么办？

Question

因此，如果您查看此代码，我在密码和电子邮件条目输入选项卡旁边使用了一个锁和用户字形图标，但它似乎不起作用。我一直在从 YouTube 视频中尝试这段代码，其他一切都运行良好 - 只是字形图标不起作用，即它根本不显示，但也没有任何错误。可能是什么问题？（PS 我正在使用可能会影响这一点的 Mac 机柜）

 <div class = "container">
            <div class = "row">
                <div class = "col-md-5">
                    <h1 class = "text-center">Log-in form</h1>
                    <label class = "label control - label"> User E-mail</label>
                    <div class = "input-group">
                        <span class = "input-group-addon"><span class = "glyphicon glyphicon-user"></span></span>
                        <input type = "text" class = "form-control" name = "mail" placeholder="E-mail">
                    </div>
                    <label class = "label control - label"> User Password</label>
                    <div class = "input-group">
                        <span class = "input-group-addon"><span class = "glyphicon glyphicon-lock"></span></span>
                        <input type = "password" class = "form-control" name = "pass" placeholder="Password">
                    </div>
                    <div class = "row">
                        <div class = "col-md-6">
                            <input type = "checkbox"> <small>Remember me</small>
  

              </div>
                <div class = "col-md-6"> 
                    <a href = "#"><p class = "text-right">Forgot Password?</p> </a>
                </div>
            </div>
            <a href = "#"><div class = "btn btn-default">LOG IN</div></a>
            <p class = "text-center">Not a member yet? <a href = "#">Sign up</a></p>
        </div>
        <div class = "col-md-2"></div>
        <div class = "col-md-5"></div>
    </div>
</div>

标签： htmlcsstwitter-bootstrapglyphicons