04Sequential 3D card flip

<main class="stage">
  <div class="cards is-demo">
    <div class="card">Basic</div>
    <div class="card">Pro</div>
    <div class="card">Team</div>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

$duration: $dur-base;                              // 카드 한 장이 펴지는 시간
$easing: $ease-out;                                // 시작 빠르고 끝은 부드럽게
$stagger: 150ms;                                   // 카드 사이 시차

@include stage($stage-paper);

.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: $r-card;
  background: $subject-blue-deep;
  color: $subject-cream;
  font-weight: 700; font-size: clamp(11px, 3vw, 13px); line-height: 1.2; font-family: inherit;
  transform-style: preserve-3d;
}

// 반복 재생은 데모 상태에서만 — 정지 상태의 카드는 불투명해야 글자가 읽힌다(크림 글자 · 진파랑 면 5.98:1)
.cards.is-demo .card { animation: flip-loop $dur-loop $easing infinite; }

@for $i from 1 through 3 {
  .cards.is-demo .card:nth-child(#{$i}) { animation-delay: ($i - 1) * $stagger; }
}

@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; }
}

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;
  }
}

import styles from "./CardFlipSequence.module.scss";

export type CardFlipSequenceProps = {
  cards: string[];
  /** 카드 사이 시차 ms (기본 150ms) */
  stagger?: number;
  duration?: number;
  easing?: string;
};

export default function CardFlipSequence({ cards, stagger = 150 }: CardFlipSequenceProps) {
  return (
    <div className={styles.cards}>
      {cards.map((label, i) => (
        <div key={label} className={styles.card} style={{ animationDelay: `${i * stagger}ms` }}>
          {label}
        </div>
      ))}
    </div>
  );
}