Centers any element on a page

jQuery.center.js

(function($, window) {
  var $w = $(window);
  
  $.fn.center = function() {
    this.css({
      position: "absolute",
      left: Math.max(0, ($w.width() - this.outerWidth()) / 2 + $(window).scrollTop()) + "px",
      top: Math.max(0, ($w.height() - this.outerHeight()) / 2 + $(window).scrollTop()) + "px"
    });
  };
})(jQuery, window);