//指定条目数
img = new Array(8);
//条目内容
img[0] = 'wallpaper/img0.jpg';
img[1] = 'wallpaper/img1.jpg';
img[2] = 'wallpaper/img2.jpg';
img[3] = 'wallpaper/img3.jpg';
img[4] = 'wallpaper/img4.jpg';
img[5] = 'wallpaper/img5.jpg';
img[6] = 'wallpaper/img6.jpg';
img[7] = 'wallpaper/img7.jpg';
img[8] = 'wallpaper/img8.jpg';
img[9] = 'wallpaper/img9.jpg';
img[10] = 'wallpaper/img10.jpg';
img[11] = 'wallpaper/img11.jpg';
img[12] = 'wallpaper/img12.jpg';

index = Math.floor(Math.random() * img.length);
document.write("<style>.img {border: 1px solid #D0D9DD; background: white url("+img[index]+") no-repeat scroll 50% 50%; height: 512px;}</style>");