title: Parallax background image for top-bottom and not right-left
body: <p>I wrote a script that changes the BG position as you scroll down, its works good for left and right positions but i cant seem to reach the syntax that will allow me to parallax the background-position top or bottom - instead of right and left.</p>
  
  <p>here is my code:</p>
  
  <pre><code>function parallax(){
      var scrolled = $(window).scrollTop();
      $('section.intro .custombg').css('background-position',(scrolled * -0.2) + 'px');}
      $(window).scroll(function(e){
          parallax();
      });
  }
  </code></pre>