Hi.
I am making template with fixed menu on top, all works ok except I cant get background color of header to be changed once page scrolls, to avoid elements under menu to be visible.
I am using something like this but not working, anyone have idea?

jQuery(document).ready(function(){       

   var scroll_start = 0;

   var startchange = $('#startchange');

   var offset = startchange.offset();

    if (startchange.length){

   $(document).scroll(function() { 

      scroll_start = $(this).scrollTop();

      if(scroll_start > offset.top) {

          $("#t3-mainnav").css('background-color', '#000000');

       } else {

          $("#t3-mainnav").css('background-color', 'transparent');

       }

   });

    }

});