html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

.link {
  position: relative;
  display: inline-block;
  padding: 6px 2px;
  font: 800 30px/1.2 inherit;
  color: #fff7e6;
  text-decoration: none;
}
.link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 3px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 260ms cubic-bezier(0.2, 0.8, 0.2, 1);
}
.link:hover::after, .link:focus-visible::after {
  transform: scaleX(1);
  transform-origin: left;
}
.link.is-demo::after {
  animation: underline-loop 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@keyframes underline-loop {
  0% {
    transform: scaleX(0);
    transform-origin: left;
  }
  35%, 55% {
    transform: scaleX(1);
    transform-origin: left;
  }
  56% {
    transform: scaleX(1);
    transform-origin: right;
  }
  90%, 100% {
    transform: scaleX(0);
    transform-origin: right;
  }
}
@media (prefers-reduced-motion: reduce) {
  .link::after, .link.is-demo::after {
    transition: none;
    animation: none;
  }
  .link:hover::after {
    transform: scaleX(1);
  }
}