html, body {
    height: 100%;
    width: 100%;
    overflow: hidden;
    margin: 0;
    padding: 0;
}

.bg-404 {
    margin-top: 7%;
    width: 1200px;
    height: 546px;
    background: url(/images/404.jpg) no-repeat left top;
    background-size: cover;
}

    .bg-404 .msg {
        color: #6f6f6f;
        padding-top: 29%;
        font-size: 21px;
    }

.btn-404 {
    margin-left: 0%;
    margin-top: 9%;
    width: 14%;
    height: 10%;
    cursor: pointer;
}