.parallax {
  position: relative;
  overflow: hidden;
}

.parallax::after {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  z-index: -1;
  content: ' ';
  background-attachment: fixed;
  background-position: center;
  background-size: cover;
  background-repeat: no-repeat;
}

@media screen and (max-width: 757px) {
  .parallax::after {
    background-attachment: scroll;
  }
}