06Layered depth cards

<main class="stage is-demo">
  <div class="depthcards">
    <div class="depthcards__card depthcards__card--3" aria-hidden="true"></div>
    <div class="depthcards__card depthcards__card--2" aria-hidden="true"></div>
    <div class="depthcards__card depthcards__card--1">
      <span>Stacked cards</span>
    </div>
  </div>
</main>

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

// ── 변수 3개. 변형은 이것만 바꾼다 ──────────────────────────
$peel: 34px;                                     // 맨 앞 카드가 밀려나는 거리
$scale-step: .06;                                // 뒤 카드일수록 커지는 폭
$color: $subject-ink;                            // 카드 색 (yellow 무대라 ink)

@include stage($stage-yellow);

.depthcards {
  position: relative;
  width: 100%;
  height: 100%;
  display: grid;
  place-items: center;
}
.depthcards__card {
  position: absolute;
  width: 168px;
  height: 108px;
  border-radius: $r-card;
  box-shadow: $shadow-raised;
  display: grid;
  place-items: center;
  font: 700 clamp(13px, 4vw, 15px)/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;

  &--3 {
    background: rgba($color, .28);
    transform: translateY(18px) scale(.88);
    @supports (animation-timeline: scroll()) { animation: peel-3 linear both; animation-timeline: scroll(root); }
  }
  &--2 {
    background: rgba($color, .58);
    transform: translateY(9px) scale(.94);
    @supports (animation-timeline: scroll()) { animation: peel-2 linear both; animation-timeline: scroll(root); }
  }
  &--1 {
    background: $color;
    color: #fff;
    @supports (animation-timeline: scroll()) { animation: peel-1 linear both; animation-timeline: scroll(root); }
  }
}

// ── 실제 사용 코드: 앞 카드일수록 더 멀리, 더 빨리 밀려난다 ──
@keyframes peel-1 { from { transform: translateY(0) scale(1); }        to { transform: translateY(-#{$peel}) scale(1); } }
@keyframes peel-2 { from { transform: translateY(9px) scale(.94); }    to { transform: translateY(9px - $peel) scale(.94 + $scale-step); } }
@keyframes peel-3 { from { transform: translateY(18px) scale(.88); }   to { transform: translateY(18px - $peel * 1.4) scale(.88 + $scale-step * 2); } }

// ── 데모(.is-demo): 왕복 루프로 흉내 ────────
.stage.is-demo .depthcards__card--1 { animation: loop-1 $dur-loop ease-in-out infinite; }
.stage.is-demo .depthcards__card--2 { animation: loop-2 $dur-loop ease-in-out infinite; }
.stage.is-demo .depthcards__card--3 { animation: loop-3 $dur-loop ease-in-out infinite; }
@keyframes loop-1 { 0%, 100% { transform: translateY(0) scale(1); }      50% { transform: translateY(-$peel) scale(1); } }
@keyframes loop-2 { 0%, 100% { transform: translateY(9px) scale(.94); }  50% { transform: translateY(9px - $peel) scale(.94 + $scale-step); } }
@keyframes loop-3 { 0%, 100% { transform: translateY(18px) scale(.88); } 50% { transform: translateY(18px - $peel * 1.4) scale(.88 + $scale-step * 2); } }

@media (prefers-reduced-motion: reduce) {
  .depthcards__card--1, .depthcards__card--2, .depthcards__card--3,
  .stage.is-demo .depthcards__card--1, .stage.is-demo .depthcards__card--2, .stage.is-demo .depthcards__card--3 {
    animation: none !important;
  }
  .depthcards__card--1 { transform: translateY(0) scale(1); }
  .depthcards__card--2 { transform: translateY(9px) scale(.94); }
  .depthcards__card--3 { transform: translateY(18px) scale(.88); }
}

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);
}

.depthcards {
  position: relative;
  width: 100%;
  height: 100%;
  display: grid;
  place-items: center;
}

.depthcards__card {
  position: absolute;
  width: 168px;
  height: 108px;
  border-radius: 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  display: grid;
  place-items: center;
  font: 700 clamp(13px, 4vw, 15px)/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}
.depthcards__card--3 {
  background: rgba(23, 20, 26, 0.28);
  transform: translateY(18px) scale(0.88);
}
@supports (animation-timeline: scroll()) {
  .depthcards__card--3 {
    animation: peel-3 linear both;
    animation-timeline: scroll(root);
  }
}
.depthcards__card--2 {
  background: rgba(23, 20, 26, 0.58);
  transform: translateY(9px) scale(0.94);
}
@supports (animation-timeline: scroll()) {
  .depthcards__card--2 {
    animation: peel-2 linear both;
    animation-timeline: scroll(root);
  }
}
.depthcards__card--1 {
  background: #17141a;
  color: #fff;
}
@supports (animation-timeline: scroll()) {
  .depthcards__card--1 {
    animation: peel-1 linear both;
    animation-timeline: scroll(root);
  }
}

@keyframes peel-1 {
  from {
    transform: translateY(0) scale(1);
  }
  to {
    transform: translateY(-34px) scale(1);
  }
}
@keyframes peel-2 {
  from {
    transform: translateY(9px) scale(0.94);
  }
  to {
    transform: translateY(-25px) scale(1);
  }
}
@keyframes peel-3 {
  from {
    transform: translateY(18px) scale(0.88);
  }
  to {
    transform: translateY(-29.6px) scale(1);
  }
}
.stage.is-demo .depthcards__card--1 {
  animation: loop-1 2s ease-in-out infinite;
}

.stage.is-demo .depthcards__card--2 {
  animation: loop-2 2s ease-in-out infinite;
}

.stage.is-demo .depthcards__card--3 {
  animation: loop-3 2s ease-in-out infinite;
}

@keyframes loop-1 {
  0%, 100% {
    transform: translateY(0) scale(1);
  }
  50% {
    transform: translateY(-34px) scale(1);
  }
}
@keyframes loop-2 {
  0%, 100% {
    transform: translateY(9px) scale(0.94);
  }
  50% {
    transform: translateY(-25px) scale(1);
  }
}
@keyframes loop-3 {
  0%, 100% {
    transform: translateY(18px) scale(0.88);
  }
  50% {
    transform: translateY(-29.6px) scale(1);
  }
}
@media (prefers-reduced-motion: reduce) {
  .depthcards__card--1, .depthcards__card--2, .depthcards__card--3,
  .stage.is-demo .depthcards__card--1, .stage.is-demo .depthcards__card--2, .stage.is-demo .depthcards__card--3 {
    animation: none !important;
  }
  .depthcards__card--1 {
    transform: translateY(0) scale(1);
  }
  .depthcards__card--2 {
    transform: translateY(9px) scale(0.94);
  }
  .depthcards__card--3 {
    transform: translateY(18px) scale(0.88);
  }
}

import type { CSSProperties, ReactNode } from "react";
import styles from "./DepthCards.module.scss";

export type DepthCardsProps = {
  /** 맨 앞 카드 라벨 */
  children: ReactNode;
  /** 맨 앞 카드가 밀려나는 거리 (기본 34px) */
  peel?: number;
  /** 뒤 카드일수록 커지는 폭 (기본 .06) */
  scaleStep?: number;
  className?: string;
};

type Vars = CSSProperties & { "--peel"?: string; "--scale-step"?: string };

export default function DepthCards({
  children,
  peel = 34,
  scaleStep = 0.06,
  className = "",
}: DepthCardsProps) {
  const vars: Vars = { "--peel": `${peel}px`, "--scale-step": `${scaleStep}` };

  return (
    <div className={`${styles.wrap} ${className}`} style={vars}>
      <div className={`${styles.card} ${styles.card3}`} aria-hidden="true" />
      <div className={`${styles.card} ${styles.card2}`} aria-hidden="true" />
      <div className={`${styles.card} ${styles.card1}`}>{children}</div>
    </div>
  );
}