title: Change value data attribute with mediaquery
body: <p>I create my website and i've got a problem with an attribute of a div.
  I try to change the value when the screen is small.</p>
  
  <p>My css mediaquery:</p>
  
  <pre><code>@media screen and (min-width: 1000px) and (max-width: 2000px) {
  #my-content { display: block; }
  #my-slider {width: 670px;}
  
  }
  
  @media screen and (min-width: 0px) and (max-width: 1000px) {
  #my-content { display: none; }   /* hide it elsewhere */
  #my-text {font-size: 26px;}
  #my-slider {content: attr(data-x : 700) ;}
  }
  </code></pre>
  
  <p>My html :</p>
  
  <pre><code>&lt;div id="my-slider" class="caption sfb" data-x="500" data-y="0" data-speed="900" data-start="900" data-easing="easeOutSine"&gt;&lt;img src="code1.jpg" width="670px" height="500px"  alt="" /&gt;&lt;/div&gt;
  </code></pre>
  
  <p>I want to change the data-x but don't work with all possibilities i've found...Can you help me? Thanks.</p>