(function($){$.fn.parallax=function(options){var windowHeight=$(window).height();var settings=$.extend({speed:0.15},options);return this.each(function(){var $this=$(this);$(document).scroll(function(){var scrollTop=$(window).scrollTop();var offset=$this.offset().top;var height=$this.outerHeight();if(offset+height<=scrollTop||offset>=scrollTop+windowHeight)return;var yBgPosition=Math.round((offset-scrollTop)*settings.speed);$this.css('background-position','center '+yBgPosition+'px');});});};}(jQuery));