07Chữ mờ lùi khi cuộn

<main class="stage is-demo">
  <div class="hero">
    <h1 class="hero__title">Scroll to reveal.</h1>
    <p class="hero__sub">The old headline recedes behind the next section.</p>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;   // 2s — 물러남 한 바퀴
$easing: $ease-out;
$color: $subject-cream;

@include stage($stage-orange);

// 실제 서비스라면 scroll-timeline / animation-timeline: view() 로 스크롤 진행률에 직접 묶지만,
// 브라우저 지원 차이가 커서(blog-demo 규칙 6) 데모는 같은 모양을 keyframes 루프로 대신한다 (사실.md 명시)
.hero {
  box-sizing: border-box;
  max-width: clamp(220px, 78vw, 360px);
  text-align: center;
  display: grid;
  gap: $sp-3;
}

.hero__title { margin: 0; color: $color; font-weight: 800; font-size: clamp(20px, 6vw, 28px); line-height: 1.25; font-family: inherit; }
.hero__sub { margin: 0; color: $subject-ink; font-weight: 500; font-size: clamp(12px, 3.4vw, 13px); line-height: 1.5; font-family: inherit; }

.stage.is-demo .hero { animation: recede $duration $easing infinite; transform-origin: center top; }

@keyframes recede {
  0%   { opacity: 1;   transform: scale(1)   translateY(0); }
  55%  { opacity: .15; transform: scale(.85) translateY(-$sp-10); }
  100% { opacity: 1;   transform: scale(1)   translateY(0); }
}

@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .hero { 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: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.hero {
  box-sizing: border-box;
  max-width: clamp(220px, 78vw, 360px);
  text-align: center;
  display: grid;
  gap: 12px;
}

.hero__title {
  margin: 0;
  color: #fff7e6;
  font-weight: 800;
  font-size: clamp(20px, 6vw, 28px);
  line-height: 1.25;
  font-family: inherit;
}

.hero__sub {
  margin: 0;
  color: #17141a;
  font-weight: 500;
  font-size: clamp(12px, 3.4vw, 13px);
  line-height: 1.5;
  font-family: inherit;
}

.stage.is-demo .hero {
  animation: recede 2s ease-out infinite;
  transform-origin: center top;
}

@keyframes recede {
  0% {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
  55% {
    opacity: 0.15;
    transform: scale(0.85) translateY(-40px);
  }
  100% {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}
@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .hero {
    animation: none;
    opacity: 1;
    transform: none;
  }
}

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

export type ScrollFadeBehindProps = {
  title?: string;
  subtitle?: string;
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function ScrollFadeBehind({
  title = "Scroll to reveal.",
  subtitle = "The old headline recedes behind the next section.",
  duration = 2000,
  easing = "ease-out",
  color = "#fff7e6",
}: ScrollFadeBehindProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  // 실제 서비스라면 scroll-timeline / animation-timeline: view() 로 스크롤 진행률에 직접 묶는다.
  // 브라우저 지원 차이가 커서 이 컴포넌트는 같은 모양을 keyframes 루프로 대신 보여준다.
  return (
    <div className={styles.hero} style={vars}>
      <h1 className={styles.title}>{title}</h1>
      <p className={styles.sub}>{subtitle}</p>
    </div>
  );
}