:root {
  height: 100vh;
  background:
    radial-gradient(circle at 50% 50%, #0000 10vmin, #ccc 0 14vmin, #0000 0),
    linear-gradient(90deg, #fff 50%, #000 0);
  
  &::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    translate: -50% -50%;
    width: 3vmin;
    height: 36vmin;
    background: linear-gradient(90deg, #0000 50%, #0003 0), red;
    opacity:1;
    transition: opacity 1s;
  }
  
  &:hover::before {
    opacity: 0;
  }
}