body {
     background: url('https://www.cnblogs.com/images/cnblogs_com/ruishui30005921/1509235/o_%e9%aa%b7%e9%ab%85.jpg ') fixed no-repeat;
     background-position: 50% 5%;
     background-size: cover;
     opacity: 0.8;
}

#blogTitle h1 {
    font-size: 50px;
    font-weight: bold;
    line-height: 1.5em;
    margin-top: 20px;
}