body {
    color: #000;
    background: #fff;
    font-family: 'Microsoft Yahei';
    font-size: 16px;
    min-height: 101%;
    background: url(//ww2.sinaimg.cn/large/0060lm7Tly1fot2hdrlfgj31hc0u0nb2.jpg)fixed; 
    background-size: cover;
    background-repeat: no-repeat;
    opacity: 0.8;
}