body {
    color: #000;
    background: url(//images.cnblogs.com/cnblogs_com/antimony/1269224/o_9fefa2ebf9b5cae28373a1cb967a21d4.jpg) fixed;
    background-size: cover;
    background-repeat: no-repeat;
    min-height: 101%;
}
#home {
    opacity: 0.80;
    margin: 0 auto;
    background-color: #fff;
    padding: 30px;
    margin-top: 30px;
    margin-bottom: 50px;
    box-shadow: 0 2px 6px rgba(100, 100, 100, 0.3);
}