01Hide then reveal

<main class="stage">
  <header class="head is-demo">
    <span class="head__logo">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. 변형은 이것만 바꾼다 ──────────────────────────
$duration: $dur-base;                             // 숨고 나타나는 시간
$easing: $ease-out;
$color: $stage-ink;                                // 헤더 배경

// ── 데모 무대 ──────────────────────────────────────────
html, body { margin: 0; overflow: hidden; }
.stage {
  min-height: 100vh;
  margin: 0;
  background: $stage-ink;
  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: $color;
  transition: transform $duration $easing;

  &__logo { color: $subject-cream; font-weight: 800; font-size: 18px; line-height: 1; font-family: inherit; letter-spacing: .04em; }
  &__nav { display: flex; gap: 10px; span { width: 24px; height: 8px; border-radius: 4px; background: rgba(255, 255, 255, .35); } }

  // 실제 사용: 아래로 스크롤하면 위로 숨는다 (JS 가 .is-hidden 을 토글)
  &.is-hidden { transform: translateY(-100%); }
}

// ── 데모(.is-demo): 숨었다 나타났다 2초 루프 ──────────────
.head.is-demo {
  animation: hide-reveal-loop $dur-loop $easing infinite;
}
@keyframes hide-reveal-loop {
  0%, 20%  { transform: translateY(0); }
  45%, 70% { transform: translateY(-100%); }
  95%, 100% { transform: translateY(0); }
}

// ── 배경: 문서처럼 보이는 자리 ─────────────────────────
.page { padding: 24px 24px 0; }
.page__line {
  height: 12px;
  margin: 0 0 14px;
  border-radius: 4px;
  background: rgba(255, 255, 255, .12);
  &.short { width: 60%; }
}

// ── 접근성: 움직임 줄이기 설정이면 즉시 상태만 바뀐다 ────────
@media (prefers-reduced-motion: reduce) {
  .head { transition: none; }
  .head.is-demo { animation: none !important; transform: translateY(0); }
}

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

.stage {
  min-height: 100vh;
  margin: 0;
  background: #17141a;
  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: #17141a;
  transition: transform 300ms ease-out;
}
.head__logo {
  color: #fff7e6;
  font-weight: 800;
  font-size: 18px;
  line-height: 1;
  font-family: inherit;
  letter-spacing: 0.04em;
}
.head__nav {
  display: flex;
  gap: 10px;
}
.head__nav span {
  width: 24px;
  height: 8px;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.35);
}
.head.is-hidden {
  transform: translateY(-100%);
}

.head.is-demo {
  animation: hide-reveal-loop 2s ease-out infinite;
}

@keyframes hide-reveal-loop {
  0%, 20% {
    transform: translateY(0);
  }
  45%, 70% {
    transform: translateY(-100%);
  }
  95%, 100% {
    transform: translateY(0);
  }
}
.page {
  padding: 24px 24px 0;
}

.page__line {
  height: 12px;
  margin: 0 0 14px;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.12);
}
.page__line.short {
  width: 60%;
}

@media (prefers-reduced-motion: reduce) {
  .head {
    transition: none;
  }
  .head.is-demo {
    animation: none !important;
    transform: translateY(0);
  }
}

// 실제 페이지: 아래로 스크롤하면 숨기고 위로 스크롤하는 순간에만 다시 보인다 (방향 감지, 8줄)
var head = document.querySelector('.head');
var lastY = window.scrollY;
window.addEventListener('scroll', function () {
  var y = window.scrollY;
  head.classList.toggle('is-hidden', y > lastY && y > 40);
  lastY = y;
}, { passive: true });

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

export type HideRevealHeaderProps = {
  logo: string;
  children?: ReactNode;
  /** 숨고 나타나는 시간 (기본 300ms) */
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function HideRevealHeader({
  logo,
  children,
  duration = 300,
  easing = "ease-out",
  color = "#17141a",
}: HideRevealHeaderProps) {
  const ref = useRef<HTMLElement>(null);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  useEffect(() => {
    let lastY = window.scrollY;
    function onScroll() {
      const y = window.scrollY;
      ref.current?.classList.toggle("is-hidden", y > lastY && y > 40);
      lastY = y;
    }
    window.addEventListener("scroll", onScroll, { passive: true });
    return () => window.removeEventListener("scroll", onScroll);
  }, []);

  return (
    <header ref={ref} className={styles.head} style={vars}>
      <span className={styles.logo}>{logo}</span>
      <nav className={styles.nav}>{children}</nav>
    </header>
  );
}