.wrap {
    height: auto;
}

.box {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
    width: 100%;
    height: 100%;
    background: url('../img/tiger.jpg') center center no-repeat;
    background-size: cover;
    box-shadow: 0 3rem 5rem -2rem rgba(0, 0, 0, 0.8);
    z-index: 1;
    overflow: hidden;
    padding: 2% 5% !important;
}
.box .smoke {
    position: absolute;
    top: -10%;
    left: -10%;
    transform: translate3d(0, 0, 0) rotate(0.01deg);
    width: 120%;
    height: 120%;
    background: url("../img/tigerSmoke.png") center center no-repeat;
    background-size: cover;
    z-index: -10;
    opacity: .5;
    animation: smokebg 60s infinite alternate;
}
@keyframes smokebg {
    25% {
        transform: translate3d(100px, 0, 0) rotate(0.01deg);
    }
    50% {
        transform: translate3d(75px, -25px, 0) rotate(0.01deg);
    }
    75% {
        transform: translate3d(45px, 30px, 0) rotate(0.01deg);
    }
    100% {
        transform: translate3d(25px, -15px, 0) rotate(0.01deg);
    }
}