Result jQuery$(function() { zoom = $('.feature').css('background-size') zoom = parseFloat(zoom) / 100 size = zoom * $('.feature').width(); $(window).on('scroll', function() { fromTop = $(window).scrollTop(); newSize = size - (fromTop / 3); if (newSize > $('.feature').width()) { $('.feature').css({ '-webkit-background-size': newSize, '-moz-background-size': newSize, '-o-background-size': newSize, '