.main {
    position: relative;
}

.main-banner {
    height: 890px;
    background-position: top center;
    background-size: cover;
    color: #fff;
    letter-spacing: 5px;
}

.main-bottom-img {
    position: absolute;
    display: block;
    width: 100%;
    bottom: -2px;
}

@media (max-width:768px) {
    .main-banner {
        height: 450px;
    }
}