html, body {
  margin: 0;
  padding: 0;
  overflow: hidden;
  background: black;
}

#overlay {
  position: absolute;
  width: 100%;
  height: 100%;
  background: repeating-linear-gradient(
    0deg,
    red 0px,
    red 1px,
    black 1px,
    black 10px
  ),
  repeating-linear-gradient(
    90deg,
    lime 0px,
    lime 1px,
    black 1px,
    black 10px
  );
  animation: flicker 0.1s infinite;
}

@keyframes flicker {
  0% { filter: invert(0) hue-rotate(0deg); }
  50% { filter: invert(1) hue-rotate(180deg); }
  100% { filter: invert(0) hue-rotate(360deg); }
}