.jarallax{
    position:relative;
    z-index:0;
}
.jarallax > .jarallax-img{
    position:absolute;
    object-fit:cover;
    /* support for plugin https://github.com/bfred-it/object-fit-images */
    font-family:'object-fit: cover;';
    top:0;
    left:0;
    width:100%;
    height:100%;
    z-index:-1;
}