.bottom-bg {
  position: fixed;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 100%;

  background-image: url(https://7heia.neocities.org/bg-pixilart.png);
  background-repeat: repeat;
  background-position: bottom left;

  z-index: -9999;
  pointer-events: none;
}