弹出位置更新宽度

Question

我试图改变弹出的位置，如果屏幕宽度小于568px通过媒体的质疑，但不知何故，它不工作.. 这里; S代码： CSS：

<style type="text/css"> 
      #wrapper 
      { 
       left: 300px; 
       position: relative; 
       width:500px; 
      } 

      .popup 
      { 
       display:none; 
       width:300px; 
       border:1px solid red; 
       padding: 10px;  
       position: absolute; 
       margin: 10px 0 0 0px; 
      } 
      @media only screen and (max-device-width : 568px) { 
      .popup 
       { 
        margin: 10px 0 0 -180px; 
       } 
      } 
     </style> 

HTML：

<div id="wrapper"> 
     <a href="#" class="def">What is Lorum Ipsum?</a> 
     <div class="popup"> 
      Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum. 
     </div> 
    </div> 
    </body> 
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>  
    <script> 
    $(".def").click(function(){ 
     $(".popup").toggle(); 
    }); 
    </script> 

这里的的jsfiddle链接： http://jsfiddle.net/0sfve6t3/2/

欣赏您的意见/输入

Answer 1

尝试的jQuery：

if($(window).width() < 568){ 
    $('.popup').css('margin','10px 0 0 -180px'); 
} 

尝试CSS：

@media only screen and (max-width: 567px){ 
.popup{margin: 10px 0 0 -180px;} 
}