(function($){
	$.fn.center = function() {
		var fixed = this.css("position") === "fixed";
		this.css("top", ($(window).height() - this.height()) / 2 + (fixed ? 0 : $(window).scrollTop()) + "px");
		this.css("left", ($(window).width() - this.width()) / 2 + (fixed ? 0 : $(window).scrollLeft()) + "px");
		return this;
	};
}(jQuery));