title: Change body opacity via javascript
body: <p>I have a slider who changes the opacity for my website</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
      $(document).ready(function() {        
          $('#slider').slider({ 
          min: 0, 
          max: 1, 
          step: 0.01, 
          value: 1,
          orientation: "vertical",
               slide: function(e,ui){
  $('body').css('opacity', ui.value)
               }                
          })
      });
  &lt;/script&gt;
  </code></pre>
  
  <p>But i want to not change opacity for 2 or 3 classes inside my body. Thanks.</p>
  
  <p>LE : In the same time i want to reduce the level of opacity of some elemnts, instead of them i want a black masque. So on the entire site only .the_window and .the_trigger to be visible and the backround black. Exemple : catalog-online.ro/test/ </p>