* {
    margin: 0;
    padding: 0;
}

html {
    font-size: 62.5%;
    color: #fff;
    font-family: Helvetica Neue, PingFang SC, Microsoft YaHei, Helvetica, Arial, sans-serif;
    height: 100%;
    overflow: auto;
}


.container {
    margin: 0 auto;
    max-width: 560px;
    line-height: 0;
    position: relative;
}

.container img {
    width: 100%;
}

.btn {
    position: fixed;
    bottom: 20px;
    left: 50%;
    margin-left: -165px;
}

.btn a {
    display: block;
    width: 330px;
}