.loader {
  width: 45px;
  height: 40px;
  background: linear-gradient(
      #0000 calc(1 * 100% / 6),
      #fff 0 calc(3 * 100% / 6),
      #0000 0
    ),
    linear-gradient(
      #0000 calc(2 * 100% / 6),
      #fff 0 calc(4 * 100% / 6),
      #0000 0
    ),
    linear-gradient(
      #0000 calc(3 * 100% / 6),
      #fff 0 calc(5 * 100% / 6),
      #0000 0
    );
  background-size: 10px 400%;
  background-repeat: no-repeat;
  animation: matrix 1s infinite linear;
}

@keyframes matrix {
  0% {
    background-position: 0% 100%, 50% 100%, 100% 100%;
  }

  100% {
    background-position: 0% 0%, 50% 0%, 100% 0%;
  }
}