How to adjust jquery pop up incenter in google chrome?

i am running a blog where i have pop up for facebook like button.it was working fine with firfox and other browser but with google chrome it is coming from right hand side direction not in centered.
i dont why pls help if you can.
my blog is
http://bestofshayari.blogspot.com

You could try adding the rules in red (you may need to adjust negative margin a bit):

#gb {
  position: fixed;
  top: 10px;
  z-index: 1000;
[COLOR="#FF0000"]  left: 50%;
  margin-left: -300px;[/COLOR]
}