body{
background-image:url("https://images.cnblogs.com/cnblogs_com/Paranoid-LS/1394964/o_%E6%B4%9B%E6%B0%B4%E5%A4%A9%E4%BE%9D.png");
background-repeat:no-repeat;
background-size: cover;
background-attachment: fixed;
filter:alpha(opacity=70); -moz-opacity:0.8; -khtml-opacity: 0.8; opacity: 0.8;
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