body {
  background-color: var(--red);
  overflow: hidden;
  position: relative;
}

.wrapper {
  font-family: Antarctica;
  color: var(--dark);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100vw;
  height: 100vh;
}

.border {
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--black);
  text-transform: uppercase;
  padding: 100px;
}

.letter {
  font-size: 20rem;
  font-variation-settings: "wght" 100;
  animation-name: letter;
  animation-duration: 4s;
  animation-direction: alternate;
  animation-iteration-count: infinite;
  animation-timing-function: ease-in-out;
  animation-fill-mode: forwards;
  animation-delay: calc(1s * var(--i));
  mix-blend-mode: difference;
  color: var(--red);
  font-variation-settings: "wdth" 1, "wght" 1, "ital" 0, "CNTR" 0;
}

.letter:nth-child(odd) {
  color: var(--red);
}

@keyframes letter {
  from {
    font-variation-settings: "wdth" 1, "wght" 1, "ital" 0, "CNTR" 0;
  }

  to {
    font-variation-settings: "wdth" 100, "wght" calc(400 * var(--i)), "ital" 0,
      "CNTR" 0;
  }
}