JQuery Mobile 弹出式登录框的实现方法

<a href="#login" data-rel="popup" data-position-to="window" data-role="button">Login</a>   <div data-role="popup" id="login" data-theme="a">     <form style="padding:10px 20px;">       <h3>Please sign in</h3>       <label for="un" class="ui-hidden-accessible">Username:</label>       <input type="js" name="user" id="un" placeholder="username" />       <label for="pw" class="ui-hidden-accessible">Password:</label>       <input type="password" name="pass" id="pw" placeholder="password" />       <button type="submit" data-theme="b">Sign in</button>     </form>   </div>