.bg{
    width: 100%;
    height: 100%;
    display: block;
    position: fixed;
    top: 0;
    left: 0;
    z-index: -1;
}
.lang{
    position: fixed;
    top: 60%;
    left: 50%;
    margin-left: -200px;
    width: 400px;
    height: 45px;
}
.lang-list{
    width: 180px;
    height: 45px;
    text-align: center;
    font-size: 16px;
    line-height: 45px;
    color: #fff;
    background: #515783;
    border-radius: 20px;
    cursor: pointer;
}
.lang-list.cn{
    float: left;
}
.lang-list.en{
    float: right;
}