body {
color: #000;
background: url(https://www.cnblogs.com/images/cnblogs_com/luotai3230/1317647/o_d52a2834349b033bb3dfabc11ece36d3d539bd52.jpg) fixed;
background-size: 100% 100%;
background-repeat: no-repeat;
font-family: "Helvetica Neue",Helvetica,Verdana,Arial,sans-serif;
font-size: 12px;
min-height: 101%;
}
#home {
    opacity: 0.70;
    margin: 0 auto;
    width: 65%;
    min-width: 950px;
    background-color: #fff;
    padding: 30px;
    margin-top: 30px;
    margin-bottom: 50px;
    box-shadow: 0 2px 6px rgba(100, 100, 100, 0.3);
<style type="text/css">.reading_btn { background: #4d90fe; border: 1px solid #4d90fe; cursor: pointer; display: inline-block; vertical-align: middle; color: #f3f7fc; font-weight: bold; width: 100px; font-size: 18px; height: 45px }
.reading_btn:hover { background: #1874CD }</style>