html,body {
    width: 100vw;
    height: 100%;
    overflow-x: hidden;
}
iframe {
    width: 100%;
    height: 100vh;
    float: left;
}
.header {
    height: .6rem;
    background: #fff;
}
span {
    color: #333;
    position: absolute;
    top: .31rem;
    left: 50%;
    font-size: .16rem;
    transform: translate(-50%,0);
}
.back {
    position: absolute;
    top: .3rem;
    left: .1rem;
    width: .2rem;
    height: .2rem;
}