title: Background attachment "fixed" doesn`t work in Firefox
body: <p>I find issue with background attachment in firefox.
  I want to make my banner background fixed ( <a href="http://inkerkam.so-use.ru/" rel="noreferrer">http://inkerkam.so-use.ru/</a> ), but it doesn`t work in firefox: background displayed, but it scrolls, however in chrome it works normally. And another moment, in another block below '.content' it works normally too. </p>
  
  <p>my html:</p>
  
  <pre><code>    &lt;div class="banner"&gt;
      ...
      &lt;/div&gt;
  ...
  
      &lt;div class="content"&gt;
      ....
      &lt;/div&gt;
  </code></pre>
  
  <p>my css:</p>
  
  <pre><code>.banner {
      background: url(/template/img/banner.jpg) no-repeat fixed left top;
  }
  
  .content {
      background: url(/template/img/banner.jpg) 0px -690px fixed;
      padding: 80px 0 120px 0;
  }
  </code></pre>
  
  <p>Maybe somebody know how to solve this problem?
  Firefox version is the last one. Updates today.</p>
  
  <p>p.s. sorry for my bad english</p>