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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.flow {
  position: relative;
  width: 92px;
  height: 92px;
  list-style: none;
  margin: 0;
  padding: 0;
  perspective: 640px;
}

.flow__card {
  position: absolute;
  inset: 0;
  border-radius: 12px;
  background: #fff7e6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  animation: flow 2s ease-out infinite;
  animation-delay: calc(var(--i) * -0.4s);
}

@keyframes flow {
  0% {
    transform: translateX(-130px) translateZ(-90px) rotateY(45deg) scale(0.6);
    opacity: 0.5;
    z-index: 1;
  }
  20% {
    transform: translateX(-68px) translateZ(-40px) rotateY(35deg) scale(0.82);
    opacity: 0.85;
    z-index: 2;
  }
  40% {
    transform: translateX(0) translateZ(0) rotateY(0deg) scale(1);
    opacity: 1;
    z-index: 3;
  }
  60% {
    transform: translateX(68px) translateZ(-40px) rotateY(-35deg) scale(0.82);
    opacity: 0.85;
    z-index: 2;
  }
  80% {
    transform: translateX(130px) translateZ(-90px) rotateY(-45deg) scale(0.6);
    opacity: 0.5;
    z-index: 1;
  }
  100% {
    transform: translateX(-130px) translateZ(-90px) rotateY(45deg) scale(0.6);
    opacity: 0.5;
    z-index: 1;
  }
}
@media (prefers-reduced-motion: reduce) {
  .flow__card {
    animation: none;
    transform: translateX(0) translateZ(0) rotateY(0deg) scale(1);
    opacity: 1;
  }
}