title: media query doesn't work without screen
body: <p>I have a problem when I use media query in css3: without <code>screen</code>, meida query doesn't work.</p>
  
  <p>Here is code: </p>
  
  <pre><code>.side-menu {
      position: fixed;
      ...
      display: none;
      margin-right: 0;
      @media screen and (min-width: @screen-xs) {
          display: block;
      }
      @media and (min-width: @screen-md) {
          right: 8.1%;
      }
  }
  </code></pre>
  
  <p>Problem: the first media query works and the seconds doesn't. If I remove the screen and the first doesn't work either.</p>
  
  <p>SO, could anyone help me?</p>