.parallax {
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
  position: relative;
}

.parallax-background, .parallax-placeholder {
  filter: brightness(50%);
}

.parallax-placeholder {
  position: absolute;
  z-index: -200;
  top: 0px;
  left: 0px;
  width: 100%;
  height: 100%;
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
}