.jarallax {
  position: relative;
  z-index: 0;
}
.jarallax {
  position: relative;
  z-index: 0;
}

  .jarallax > .jarallax-img,
  picture.jarallax-img img {
    position: absolute;
    object-fit: cover;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
  }