(function(a){a.extend(a.fx.step,{backgroundPosition:function(b){function f(a){a=a.replace(/left|top/g,"0px");a=a.replace(/right|bottom/g,"100%");a=a.replace(/([0-9\.]+)(\s|\)|$)/g,"$1px$2");var b=a.match(/(-?[0-9\.]+)(px|\%|em|pt)\s(-?[0-9\.]+)(px|\%|em|pt)/);return[parseFloat(b[1],10),b[2],parseFloat(b[3],10),b[4]]}if(b.state===0&&typeof b.end=="string"){var c=a.curCSS(b.elem,"backgroundPosition");c=f(c);b.start=[c[0],c[2]];var d=f(b.end);b.end=[d[0],d[2]];b.unit=[d[1],d[3]]}var e=[];e[0]=(b.end[0]-b.start[0])*b.pos+b.start[0]+b.unit[0];e[1]=(b.end[1]-b.start[1])*b.pos+b.start[1]+b.unit[1];b.elem.style.backgroundPosition=e[0]+" "+e[1]}})})(jQuery)