if(screen.width > 800){
var screenad=screen.width-133;
document.write('<DIV ID="Layer_ad" STYLE="position:absolute; width:110; height:300; z-index:1; left: 0px; top: 130px"><img src=http://www.tmall.com.cn/ad/100x250.gif WIDTH=100 HEIGHT=250 border=0></DIV>');
document.write('<DIV ID="Layer_ad" STYLE="position:absolute; width:110; height:300; z-index:1; left: '+screenad+'px; top: 130px"><img src=http://www.tmall.com.cn/ad/100x250b.gif WIDTH=100 HEIGHT=250 border=0></DIV>');
}