html {
  background: 
    repeating-radial-gradient(#000 0 0.0001%,#fff 0 0.0002%) 50% 0/2500px 2500px,
    repeating-conic-gradient(#000 0 0.0001%,#fff 0 0.0002%) 60% 60%/2500px 2500px;
  background-blend-mode: difference;
  animation: b .2s infinite alternate;
}
@keyframes b{
  100% {background-position: 50% 0, 60% 50%}
}