#BackToTop {
    display: none;
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 50px;
    height: 50px;
    line-height: 45px;
    background-color: #fff;
    border: 1px solid #ddd;
    border-radius: 50%;
    text-align: center;
    text-decoration: none;
    color: #253a74;
    font-family: "微软雅黑";
    z-index: 111;
    cursor: pointer;
    transition: all .3s ease;
}

#BackToTop:hover {
    background-color: #253a74;
    border-color: #253a74;
    color: #fff;
}

#BackToTop i {
    font-size: 24px;
}

@media (max-width: 414px) {
    #BackToTop {
        right: 10px;
        bottom: 10px;
        width: 35px;
        height: 35px;
        line-height: 30px;
    }

    #BackToTop i {
        font-size: 18px;
    }
}