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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.cards {
  display: flex;
  gap: clamp(8px, 2.6vw, 14px);
  perspective: 600px;
}

.card {
  width: clamp(56px, 16vw, 76px);
  height: clamp(64px, 18vw, 84px);
  display: grid;
  place-items: center;
  border-radius: 16px;
  background: #0a4fe8;
  color: #fff7e6;
  font-weight: 700;
  font-size: clamp(11px, 3vw, 13px);
  line-height: 1.2;
  font-family: inherit;
  transform-style: preserve-3d;
}

.cards.is-demo .card {
  animation: flip-loop 2s ease-out infinite;
}

.cards.is-demo .card:nth-child(1) {
  animation-delay: 0ms;
}

.cards.is-demo .card:nth-child(2) {
  animation-delay: 150ms;
}

.cards.is-demo .card:nth-child(3) {
  animation-delay: 300ms;
}

@keyframes flip-loop {
  0%, 6% {
    opacity: 0;
    transform: rotateY(90deg);
  }
  26%, 66% {
    opacity: 1;
    transform: rotateY(0deg);
  }
  86%, 100% {
    opacity: 0;
    transform: rotateY(-90deg);
  }
}
@media (prefers-reduced-motion: reduce) {
  .card {
    animation: none;
    opacity: 1;
    transform: none;
  }
}