@media screen and (min-width: 800px) { 
    html {
        background-image: url("../images/qr_bg.jpg");
        background-repeat: no-repeat;
        background-size: 100% 100%;
    }
    .qr_container{
        background-color:#fafafa;
        box-shadow:0px 15px 30px rgba(0,0,0,0.4);
        width:380px;
        padding-bottom: 10px
    } 
    #qrcode canvas{
        margin-top:40px;
    }
    .logo{
        left:155px;
        top: 145px; 
    } 
}
@media screen and (max-width: 800px) { 
    .qr_container{
        width:300px;
    } 
    .logo{
        left:110px;
        top: 95px; 
    } 
}  
html {
    height: 100%;
    width: 100%;
    overflow:hidden;
}

body {
    height:100%;
    margin: 0 auto;
    font-family: "Microsoft Yahei";
    text-align:center;
    overflow:hidden;
}
.qr_container{
    position: relative; 
    margin: 0 auto; 
    text-align:center;
    top:50%;
}
.logo{
    width: 75px; 
    height: 75px; 
    position: absolute; 
    border-radius: 5px;
}
.desc{
    width: 270px; 
    margin:15px auto;
    padding:2px;
    text-align:left;
}
.desc h4{
    text-align:center;
    margin:0;
    margin-bottom:20px;
}
.desc>.font_1{
    font-size:13px;
    line-height:1.2em;
    letter-spacing:1px;
    color:#333;
}
.ad_slot_left {
    position: fixed;
    left: 30px;
    top: 30px;
    width: 160px;
    height: 600px;
}
.ad_slot_right {
    position: fixed;
    right: 30px;
    top: 30px;
    width: 250px;
    height: 250px;
}