Animating the css of an image giving different result

[atmiiou]

I have a menu and a small bar that follows which \[code\]<a>\[/code\] tag I hover in my menu.The small bar is an image and I am animating its CSS with the jQuery animate function.My problem is that my small bar position is a little bit different when I use a different browser or a different resolution.I need that bar to always fit perfectly.The problem with my fiddle is that I use an image