(function($) {
    if (!document.defaultView || !document.defaultView.getComputedStyle) {
        var oldCurCSS = jQuery.curCSS; jQuery.curCSS = function(elem, name, force) {
            if (name === 'background-position') { name = 'backgroundPosition'; }
            if (name !== 'backgroundPosition' || !elem.currentStyle || elem.currentStyle[name]) { return oldCurCSS.apply(this, arguments); }
            var style = elem.style; if (!force && style && style[name]) { return style[name]; }
            return oldCurCSS(elem, 'backgroundPositionX', force) + ' ' + oldCurCSS(elem, 'backgroundPositionY', force);
        };
    }
    var oldAnim = $.fn.animate; $.fn.animate = function(prop) {
        if ('background-position' in prop) { prop.backgroundPosition = prop['background-position']; delete prop['background-position']; }
        if ('backgroundPosition' in prop) { prop.backgroundPosition = '(' + prop.backgroundPosition; }
        return oldAnim.apply(this, arguments);
    }; function toArray(strg) { strg = strg.replace(/left|top/g, '0px'); strg = strg.replace(/right|bottom/g, '100%'); strg = strg.replace(/([0-9\.]+)(\s|\)|$)/g, "$1px$2"); var res = strg.match(/(-?[0-9\.]+)(px|\%|em|pt)\s(-?[0-9\.]+)(px|\%|em|pt)/); return [parseFloat(res[1], 10), res[2], parseFloat(res[3], 10), res[4]]; }
    $.fx.step.backgroundPosition = function(fx) {
        if (!fx.bgPosReady) {
            var start = $.curCSS(fx.elem, 'backgroundPosition'); if (!start) { start = '0px 0px'; }
            start = toArray(start); fx.start = [start[0], start[2]]; var end = toArray(fx.options.curAnim.backgroundPosition); fx.end = [end[0], end[2]]; fx.unit = [end[1], end[3]]; fx.bgPosReady = true;
        }
        var nowPosX = []; nowPosX[0] = ((fx.end[0] - fx.start[0]) * fx.pos) + fx.start[0] + fx.unit[0]; nowPosX[1] = ((fx.end[1] - fx.start[1]) * fx.pos) + fx.start[1] + fx.unit[1]; fx.elem.style.backgroundPosition = nowPosX[0] + ' ' + nowPosX[1];
    };
})(jQuery);