@mixin blackBackgroundMixin {
  .black-background {
    fill: black;
    opacity: 0;
    animation-name: black_background_animation;
    animation-delay: var(--animation-delay, 0s);
    animation-duration: var(--animation-duration, 1.5s);
    animation-timing-function: linear;
    animation-direction: alternate;
    animation-iteration-count: 2;
  }

  @keyframes black_background_animation {
    0% {
      opacity: 0;
    }
    15% {
      opacity: 0.5;
    }
    100% {
      opacity: 0.5;
    }
  }
}
