body {
    margin: 0;
    width: 100vw;
    height: 100vh;
    background: url(../img/proof-bg.jpg) no-repeat;
    background-size: 100% 100%;
}

.navgation-box {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    width: 94%;
    height: 6%;
    margin: 0 auto;
    font-size: 1.3rem;
    font-family: Source Han Sans CN;
    font-weight: bold;
    color: #FEFFFF;
}

.back-home-a {
    position: absolute;
    left: 0;
    display: block;
    float: left;
}

.left-arrow-img {
    width: 90%;
    height: 70%;
}

.proof-img-box {
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 23% auto;
    width: 94%;
    height: 67%;
    background: url(../img/proof-img-bg.jpg) no-repeat;
    background-size: 100% 100%;
}

.proof-img {
    width: 60%;
    height: 69%;
}