06Flip-card transition

<main class="stage">
  <div class="card">
    <div class="card__inner">
      <div class="card__face card__face--front">
        <span class="card__icon card__icon--sun"></span>
        <p class="card__label">Light</p>
      </div>
      <div class="card__face card__face--back">
        <span class="card__icon card__icon--moon"></span>
        <p class="card__label">Dark</p>
      </div>
    </div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────
$duration: $dur-enter;
$easing: $ease-spring;
$color: $subject-blue;

// ── 데모 무대 ───────────────────────────────
@include stage($stage-yellow);

.card {
  width: clamp(150px, 46vw, 180px); height: clamp(110px, 40vw, 140px);
  perspective: 900px;
}
.card__inner {
  position: relative; width: 100%; height: 100%; transform-style: preserve-3d;
  animation: flip $dur-loop $easing infinite;
}
.card__face {
  position: absolute; inset: 0; display: grid; place-items: center; gap: 8px;
  border-radius: $r-card; box-shadow: $shadow-raised; backface-visibility: hidden;
}
.card__face--front { background: $subject-cream; color: $subject-ink; }
.card__face--back  { background: $stage-ink; color: $subject-cream; transform: rotateY(180deg); }
.card__icon { width: 30px; height: 30px; border-radius: 50%; }
.card__icon--sun  { background: $stage-yellow; }
.card__icon--moon { background: $subject-cream; }
.card__label { margin: 0; font-weight: 600; font-size: clamp(11px, 3.2vw, 13px); line-height: 1; font-family: inherit; }

// 앞면(라이트) → 뒷면(다크) → 다시 앞면. perspective + rotateY 만 쓴다
@keyframes flip {
  0%, 15%  { transform: rotateY(0deg); }
  50%      { transform: rotateY(180deg); }
  85%, 100% { transform: rotateY(360deg); }
}

// ── 접근성: 움직임 줄이기 설정이면 앞면(라이트)에 고정 ──────────
@media (prefers-reduced-motion: reduce) {
  .card__inner { animation: none !important; transform: rotateY(0deg); }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.card {
  width: clamp(150px, 46vw, 180px);
  height: clamp(110px, 40vw, 140px);
  perspective: 900px;
}

.card__inner {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  animation: flip 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.card__face {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  gap: 8px;
  border-radius: 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  backface-visibility: hidden;
}

.card__face--front {
  background: #fff7e6;
  color: #17141a;
}

.card__face--back {
  background: #17141a;
  color: #fff7e6;
  transform: rotateY(180deg);
}

.card__icon {
  width: 30px;
  height: 30px;
  border-radius: 50%;
}

.card__icon--sun {
  background: #ffd23f;
}

.card__icon--moon {
  background: #fff7e6;
}

.card__label {
  margin: 0;
  font-weight: 600;
  font-size: clamp(11px, 3.2vw, 13px);
  line-height: 1;
  font-family: inherit;
}

@keyframes flip {
  0%, 15% {
    transform: rotateY(0deg);
  }
  50% {
    transform: rotateY(180deg);
  }
  85%, 100% {
    transform: rotateY(360deg);
  }
}
@media (prefers-reduced-motion: reduce) {
  .card__inner {
    animation: none !important;
    transform: rotateY(0deg);
  }
}

import type { CSSProperties } from "react";
import styles from "./FlipCardToggle.module.scss";

export type FlipCardToggleProps = {
  dark: boolean;
  onToggle?: () => void;
  /** 카드가 뒤집히는 시간 (기본 600ms) */
  duration?: number;
  easing?: string;
  className?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string };

export default function FlipCardToggle({
  dark,
  onToggle,
  duration = 600,
  easing = "cubic-bezier(.2,.8,.2,1)",
  className = "",
}: FlipCardToggleProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing };
  return (
    <button
      type="button"
      className={`${styles.card} ${className}`}
      style={vars}
      data-dark={dark}
      aria-label="다크모드 전환"
      onClick={onToggle}
    >
      <span className={styles.inner}>
        <span className={`${styles.face} ${styles.front}`}>라이트</span>
        <span className={`${styles.face} ${styles.back}`}>다크</span>
      </span>
    </button>
  );
}