05App-style stack push

<main class="stage">
  <div class="pages is-demo">
    <section class="page page--a">
      <p class="page__tag">MENU</p>
      <h2 class="page__title">Settings</h2>
      <p class="page__body">Account · Notifications · Billing</p>
    </section>
    <section class="page page--b">
      <p class="page__tag">MENU &gt; PUSH</p>
      <h2 class="page__title">Notification settings</h2>
      <p class="page__body">Push · Email · SMS</p>
    </section>
    <div class="dim"></div>
  </div>
</main>

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

// ── 변수 3개. 변형은 이것만 바꾼다 (값은 토큰에서 받는다) ──────
$duration: $dur-base;
$easing: $ease-out;
$color: $subject-blue-deep;

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

.pages { position: relative; width: min(300px, 88%); height: 150px; border-radius: $r-card; overflow: hidden; box-shadow: $shadow-raised; }
.page {
  position: absolute; inset: 0; box-sizing: border-box;
  display: flex; flex-direction: column; justify-content: center; gap: 6px;
  padding: clamp(12px, 5vw, 20px); text-align: left;
}
.page--a { background: #fff; color: $subject-ink; }
.page--b { background: $color; color: $subject-cream; }
.page__tag { margin: 0; font-weight: 700; font-size: clamp(9px, 2.6vw, 11px); line-height: 1; font-family: inherit; letter-spacing: .12em; }
.page__title { margin: 0; font-weight: 700; font-size: clamp(14px, 4.2vw, 18px); line-height: 1.3; font-family: inherit; }
.page__body { margin: 0; font-weight: 400; font-size: clamp(11px, 3.2vw, 13px); line-height: 1.5; font-family: inherit; }
.dim { position: absolute; inset: 0; background: $subject-ink; opacity: 0; pointer-events: none; }

// 새 화면이 오른쪽에서 쌓이듯 밀려 들어오고, 이전 화면은 살짝 줄어들며 어두워진다.
.page--a { animation: push-back $dur-loop $easing infinite; transform-origin: left center; } // 규칙8: 새 화면이 오른쪽에서 들어오니 이전 화면은 왼쪽 변을 축으로 물러난다
.page--b { animation: push-front $dur-loop $easing infinite; transform: translateX(100%); }
.dim { animation: push-dim $dur-loop $easing infinite; }

@keyframes push-back {
  0%, 5% { transform: scale(1); }
  50% { transform: scale(.94); }
  95%, 100% { transform: scale(1); }
}
@keyframes push-front {
  0%, 5% { transform: translateX(100%); }
  50% { transform: translateX(0); }
  95%, 100% { transform: translateX(100%); }
}
@keyframes push-dim {
  0%, 5% { opacity: 0; }
  50% { opacity: .18; }
  95%, 100% { opacity: 0; }
}

// ── 접근성: 움직임 줄이기 설정이면 최종 상태만 고정으로 ────────
@media (prefers-reduced-motion: reduce) {
  .page--a, .page--b, .dim { animation: none !important; }
  .page--b { transform: translateX(100%); }
  .dim { opacity: 0; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.pages {
  position: relative;
  width: min(300px, 88%);
  height: 150px;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.page {
  position: absolute;
  inset: 0;
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 6px;
  padding: clamp(12px, 5vw, 20px);
  text-align: left;
}

.page--a {
  background: #fff;
  color: #17141a;
}

.page--b {
  background: #0a4fe8;
  color: #fff7e6;
}

.page__tag {
  margin: 0;
  font-weight: 700;
  font-size: clamp(9px, 2.6vw, 11px);
  line-height: 1;
  font-family: inherit;
  letter-spacing: 0.12em;
}

.page__title {
  margin: 0;
  font-weight: 700;
  font-size: clamp(14px, 4.2vw, 18px);
  line-height: 1.3;
  font-family: inherit;
}

.page__body {
  margin: 0;
  font-weight: 400;
  font-size: clamp(11px, 3.2vw, 13px);
  line-height: 1.5;
  font-family: inherit;
}

.dim {
  position: absolute;
  inset: 0;
  background: #17141a;
  opacity: 0;
  pointer-events: none;
}

.page--a {
  animation: push-back 2s ease-out infinite;
  transform-origin: left center;
}

.page--b {
  animation: push-front 2s ease-out infinite;
  transform: translateX(100%);
}

.dim {
  animation: push-dim 2s ease-out infinite;
}

@keyframes push-back {
  0%, 5% {
    transform: scale(1);
  }
  50% {
    transform: scale(0.94);
  }
  95%, 100% {
    transform: scale(1);
  }
}
@keyframes push-front {
  0%, 5% {
    transform: translateX(100%);
  }
  50% {
    transform: translateX(0);
  }
  95%, 100% {
    transform: translateX(100%);
  }
}
@keyframes push-dim {
  0%, 5% {
    opacity: 0;
  }
  50% {
    opacity: 0.18;
  }
  95%, 100% {
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .page--a, .page--b, .dim {
    animation: none !important;
  }
  .page--b {
    transform: translateX(100%);
  }
  .dim {
    opacity: 0;
  }
}

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

export type StackPushTransitionProps = {
  /** "root": 뒤 화면만, "pushed": 새 화면이 쌓인 상태 */
  active: "root" | "pushed";
  root: ReactNode;
  pushed: ReactNode;
  /** 새 화면이 밀려 들어오는 시간 (기본 300ms) */
  duration?: number;
  easing?: string;
  color?: string;
  className?: string;
};

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

export default function StackPushTransition({
  active,
  root,
  pushed,
  duration = 300,
  easing = "ease-out",
  color = "#0a4fe8",
  className = "",
}: StackPushTransitionProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <div className={`${styles.pages} ${className}`} style={vars} data-active={active}>
      <section className={styles.root}>{root}</section>
      <div className={styles.dim} />
      <section className={styles.pushed}>{pushed}</section>
    </div>
  );
}