body{
background-image:url("//wx4.sinaimg.cn/mw1024/4b884e9egy1fllbdo9rcsj20hs0vkwx5.jpg");
background-repeat:no-repeat;
background-size:100%;
background-attachment:fixed;
filter:alpha(opacity=80); -moz-opacity:0.8; -khtml-opacity: 0.8; opacity: 0.8;
}