:root {
  height: 100vh;
  background:
    repeating-linear-gradient(#fff 0 8.3333vh, #000 0 16.6666vh);
  display: flex;
  justify-content: space-evenly;
  
  &::before, &::after {
    content: "";
    width: 20vw;
    background: #888;
    mix-blend-mode: darken;
  }
  
  &::after {
    mix-blend-mode: lighten;
  }
}