.background {
  position: absolute;
  inset: 0;
  background: black url("../assets/bg_repeatable.png") repeat;
  z-index: 0;
}

.background::before {
  content: "";
  position: absolute;
  top: -60%;
  left: 0;
  width: 100%;
  height: 60%;

  background: rgb(255, 60, 60);

  mask-image: linear-gradient(
    to bottom,
    transparent,
    black 20%,
    black 80%,
    transparent
  );

  mix-blend-mode: soft-light;
  filter: brightness(1.5) saturate(0.8);

  pointer-events: none;
  z-index: 1;

  animation: wave 9s infinite linear;
}

@keyframes wave {
  0% {
    transform: translateY(-120%);
    opacity: 0;
    background: rgb(255, 50, 0);
  }

  15% {
    opacity: 1;
  }

  50% {
    background: rgb(255, 85, 0);
  }

  80% {
    transform: translateY(170%);
    background: rgb(255, 110, 0);
    opacity: 1;
  }

  100% {
    transform: translateY(240%);
    opacity: 0;
  }
}