#home {
opacity: 0.8;
margin: 0 auto;
width: 85%;
min-width: 950px;
background-color: #fff;
padding: 30px;
margin-top: 0;
margin-bottom: 50px;
box-shadow: 0 2px 6px rgba(100, 100, 100, 0.3);
}
body {
color: #000;
background: url(https://www.cnblogs.com/images/cnblogs_com/liangzb310/1482540/o_%e5%be%ae%e4%bf%a1%e5%9b%be%e7%89%87_20190614181255.jpg
) fixed;
background-size: 100%;
background-repeat: no-repeat;
font-family: "Helvetica Neue",Helvetica,Verdana,Arial,sans-serif;
font-size: 12px;
min-height: 101%;
}
#c{
   position: fixed; 
   top:0; 
   left: 0; 
   z-index:-1; 
   opacity:0.8;
}