title: jQuery CSS Opacity
body: <p>What's wrong? I want to change the opacity if <code>#nav .drop</code> is <code>display:block;</code></p>
  
  <pre><code>jQuery(document).ready(function(){
      if (jQuery('#nav .drop').css('display') === 'block') {
          jQuery('#main').css('opacity') = '0.6';
      }
  });
  </code></pre>