body {
color: #000;
background: url(https://images.cnblogs.com/cnblogs_com/blogs/747476/galleries/2218866/o_220918024552_ea98bce0gy1h00e3uzl9aj21z418gb29.jpg) fixed;
background-size: 100%;
background-repeat: no-repeat;
font-family: "Helvetica Neue",Helvetica,Verdana,Arial,sans-serif;
font-size: 12px;
min-height: 101%;
}

#home{
     opacity:0.9; //0.0到1随便设置，越低越透明
}