jQuery CSS Opacity

Question

What's wrong? I want to change the opacity if #nav .drop is display:block;

jQuery(document).ready(function(){     if (jQuery('#nav .drop').css('display') === 'block') {         jQuery('#main').css('opacity') = '0.6';     } }); 

Answer 1

jQuery('#main').css('opacity') = '0.6'; 

should be

jQuery('#main').css('opacity', '0.6'); 

Update:

http://jsfiddle.net/GegMk/ if you type in the text box. Click away, the opacity changes.