.landing_img_wrapper{
    position: relative;
}

.landing_img_wrapper > img{
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    opacity: 0;
}

.landing_img_wrapper > img:first-child{
    position: static;
}

@media screen and (max-width: 900px){
    .landing_img_wrapper{
        max-width: 480px;
        margin: auto;
        margin-top: 2em;
    }
}