body {
    color: #000;
    background: #fff;
    font-family: 'PingFang SC','Helvetica Neue','Helvetica','Arial','Microsoft Yahei',sans-serif;
    font-size: 12px;
    min-height: 101%;
    background: url(https://github.com/EternalSummer/iCode/blob/master/bgc.jpg?raw=true) top center #cbdcec;
    background-size: 100% auto;
    background-attachment: fixed;
}
#main{
    background: rgba(255,255,255,0.5);
}
#mainContent{
    background: rgba(255,255,255,0.5);
}