jQuery Sticky Navigation Center during scrolling

[DaNaJOnAs]

How can i set the width of the Navigation during scrolling. The Navigation fits 100% width during scrolling. If i set the width to 500px than its left:0 positioned. At left i cant set auto center the Navigation.http://jsfiddle.net/aY8a7/\[code\]$(function() { var sticky_navigation_offset_top = $('#sticky_navigation').offset().top; var sticky_navigation = function(){ var scroll_top = $(window).scrollTop(); // our current vertical position from the top if (scroll_top > sticky_navigation_offset_top) { $('#sticky_navigation').css({ 'position': 'fixed', 'top':0, 'left':0 }); } else { $('#navigation_menu').css({ 'position': 'relative' }); } }; sticky_navigation(); $(window).scroll(function() { sticky_navigation(); });});\[/code\]