04Logo-only shrink

<main class="stage">
  <header class="head is-demo">
    <span class="head__logo"><span class="head__mark" aria-hidden="true"></span>GODRICH</span>
    <nav class="head__nav" aria-hidden="true"><span></span><span></span><span></span></nav>
  </header>
  <div class="page">
    <p class="page__line"></p>
    <p class="page__line"></p>
    <p class="page__line short"></p>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-enter;                             // 로고가 줄어드는 시간
$easing: $ease-out;
$scale-to: .72;                                    // 줄어든 비율

// ── 데모 무대 ──────────────────────────────────────────
html, body { margin: 0; overflow: hidden; }
.stage {
  min-height: 100vh;
  margin: 0;
  background: $stage-paper;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

// 헤더 높이·배경은 고정. 로고만 scale 로 줄어든다 (레이아웃은 절대 바뀌지 않는다)
.head {
  position: sticky;
  top: 0;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(16px, 5vw, 24px);
  background: $subject-blue;

  &__logo {
    display: flex; align-items: center; gap: 10px;
    color: $subject-cream; font-weight: 800; font-size: 20px; line-height: 1; font-family: inherit; letter-spacing: .04em;
    transform-origin: left center; // 규칙8: 헤더 좌변 붙은 로고 축소
  }
  &__mark { width: 40px; height: 40px; border-radius: $r-control; background: $subject-cream; }
  &__nav { display: flex; gap: 10px; span { width: 24px; height: 8px; border-radius: 4px; background: rgba(255, 255, 255, .35); } }

  // 실제 사용: 문서 스크롤이 진행되는 동안 로고만 줄어든다
  @supports (animation-timeline: scroll()) {
    .head__logo { animation: logo-shrink linear both; animation-timeline: scroll(root); animation-range: 0 150px; }
  }
}

@keyframes logo-shrink {
  from { transform: scale(1); }
  to   { transform: scale($scale-to); }
}

// ── 데모(.is-demo): 로고가 줄었다 늘었다 2초 루프 ──────────
.head.is-demo .head__logo {
  animation: logo-shrink-loop $dur-loop $easing infinite;
}
@keyframes logo-shrink-loop {
  0%, 15%  { transform: scale(1); }
  45%, 70% { transform: scale($scale-to); }
  95%, 100% { transform: scale(1); }
}

// ── 배경: 문서처럼 보이는 자리 ─────────────────────────
.page { padding: 24px 24px 0; }
.page__line {
  height: 12px;
  margin: 0 0 14px;
  border-radius: 4px;
  background: rgba($stage-ink, .1);
  &.short { width: 60%; }
}

@media (prefers-reduced-motion: reduce) {
  .head.is-demo .head__logo { animation: none !important; transform: scale($scale-to); }
}

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

.stage {
  min-height: 100vh;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

.head {
  position: sticky;
  top: 0;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(16px, 5vw, 24px);
  background: #2f6df6;
}
.head__logo {
  display: flex;
  align-items: center;
  gap: 10px;
  color: #fff7e6;
  font-weight: 800;
  font-size: 20px;
  line-height: 1;
  font-family: inherit;
  letter-spacing: 0.04em;
  transform-origin: left center;
}
.head__mark {
  width: 40px;
  height: 40px;
  border-radius: 12px;
  background: #fff7e6;
}
.head__nav {
  display: flex;
  gap: 10px;
}
.head__nav span {
  width: 24px;
  height: 8px;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.35);
}
@supports (animation-timeline: scroll()) {
  .head .head__logo {
    animation: logo-shrink linear both;
    animation-timeline: scroll(root);
    animation-range: 0 150px;
  }
}

@keyframes logo-shrink {
  from {
    transform: scale(1);
  }
  to {
    transform: scale(0.72);
  }
}
.head.is-demo .head__logo {
  animation: logo-shrink-loop 2s ease-out infinite;
}

@keyframes logo-shrink-loop {
  0%, 15% {
    transform: scale(1);
  }
  45%, 70% {
    transform: scale(0.72);
  }
  95%, 100% {
    transform: scale(1);
  }
}
.page {
  padding: 24px 24px 0;
}

.page__line {
  height: 12px;
  margin: 0 0 14px;
  border-radius: 4px;
  background: rgba(23, 20, 26, 0.1);
}
.page__line.short {
  width: 60%;
}

@media (prefers-reduced-motion: reduce) {
  .head.is-demo .head__logo {
    animation: none !important;
    transform: scale(0.72);
  }
}

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

export type LogoShrinkHeaderProps = {
  logo: string;
  children?: ReactNode;
  /** 로고가 줄어드는 시간 (기본 600ms) — 실제 사용은 scroll() 타임라인이 대신한다 */
  duration?: number;
  easing?: string;
  /** 줄어든 비율 (기본 .72) */
  scaleTo?: number;
};

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

export default function LogoShrinkHeader({
  logo,
  children,
  duration = 600,
  easing = "ease-out",
  scaleTo = 0.72,
}: LogoShrinkHeaderProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--scale-to": scaleTo };

  return (
    <header className={styles.head} style={vars}>
      <span className={styles.logo}>
        <span className={styles.mark} aria-hidden="true" />
        {logo}
      </span>
      <nav className={styles.nav}>{children}</nav>
    </header>
  );
}