09通知バッジの出現

<main class="stage">
  <header class="head is-demo">
    <span class="head__logo">GODRICH</span>
    <span class="head__icon" aria-hidden="true">
      <span class="head__dot"></span>
    </span>
  </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-quick;                             // 점이 튀어나오는 시간
$easing: $ease-pop;
$color: $subject-blue;                             // 알림 점 색

// ── 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: $stage-ink;

  &__logo { color: $subject-cream; font-weight: 800; font-size: 18px; line-height: 1; font-family: inherit; letter-spacing: .04em; }
  &__icon {
    position: relative;
    display: inline-flex;
    width: 28px;
    height: 28px;
    border-radius: $r-sm;
    border: 2px solid $subject-cream;
  }
  &__dot {
    position: absolute;
    top: -6px;
    right: -6px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: $color;
    transform: scale(0);
    opacity: 0;
    transition: transform $duration $easing, opacity $duration $easing;
  }

  // 실제 사용: 스크롤을 넘으면 점이 튀어나오고, 그 뒤로는 은은하게 계속 맥박친다
  &.is-scrolled &__dot {
    transform: scale(1);
    opacity: 1;
    animation: dot-pulse-real 1.6s ease-in-out infinite;
  }
}
@keyframes dot-pulse-real {
  0%, 100% { transform: scale(1); opacity: 1; }
  50%      { transform: scale(1.3); opacity: .7; }
}

// ── 데모(.is-demo): 팝인 + 맥박 + 사라짐 2초 루프 ──────
.head.is-demo .head__dot {
  animation: dot-demo-loop $dur-loop $easing infinite;
}
@keyframes dot-demo-loop {
  0%   { transform: scale(0);    opacity: 0; }
  10%  { transform: scale(1.6);  opacity: 1; }
  18%  { transform: scale(1);    opacity: 1; }
  38%  { transform: scale(1.3);  opacity: .7; }
  52%  { transform: scale(1);    opacity: 1; }
  72%  { transform: scale(1.3);  opacity: .7; }
  86%  { transform: scale(1);    opacity: 1; }
  96%  { transform: scale(.4);   opacity: 0; }
  100% { transform: scale(0);    opacity: 0; }
}

// ── 배경: 문서처럼 보이는 자리 ─────────────────────────
.page { padding: $sp-6 $sp-6 0; }
.page__line {
  height: 12px;
  margin: 0 0 $sp-3;
  border-radius: $r-xs;
  background: rgba($stage-paper, .12);
  &.short { width: 60%; }
}

// ── 접근성: 움직임 줄이기 설정이면 즉시 상태만 바뀐다 ────────
@media (prefers-reduced-motion: reduce) {
  .head__dot { transition: none; animation: none !important; }
  .head.is-scrolled .head__dot { transform: scale(1); opacity: 1; }
  .head.is-demo .head__dot { animation: none !important; transform: scale(1); opacity: 1; }
}

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;
}
.head__logo {
  color: #fff7e6;
  font-weight: 800;
  font-size: 18px;
  line-height: 1;
  font-family: inherit;
  letter-spacing: 0.04em;
}
.head__icon {
  position: relative;
  display: inline-flex;
  width: 28px;
  height: 28px;
  border-radius: 8px;
  border: 2px solid #fff7e6;
}
.head__dot {
  position: absolute;
  top: -6px;
  right: -6px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #2f6df6;
  transform: scale(0);
  opacity: 0;
  transition: transform 220ms cubic-bezier(0.2, 1.4, 0.4, 1), opacity 220ms cubic-bezier(0.2, 1.4, 0.4, 1);
}
.head.is-scrolled .head__dot {
  transform: scale(1);
  opacity: 1;
  animation: dot-pulse-real 1.6s ease-in-out infinite;
}

@keyframes dot-pulse-real {
  0%, 100% {
    transform: scale(1);
    opacity: 1;
  }
  50% {
    transform: scale(1.3);
    opacity: 0.7;
  }
}
.head.is-demo .head__dot {
  animation: dot-demo-loop 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
}

@keyframes dot-demo-loop {
  0% {
    transform: scale(0);
    opacity: 0;
  }
  10% {
    transform: scale(1.6);
    opacity: 1;
  }
  18% {
    transform: scale(1);
    opacity: 1;
  }
  38% {
    transform: scale(1.3);
    opacity: 0.7;
  }
  52% {
    transform: scale(1);
    opacity: 1;
  }
  72% {
    transform: scale(1.3);
    opacity: 0.7;
  }
  86% {
    transform: scale(1);
    opacity: 1;
  }
  96% {
    transform: scale(0.4);
    opacity: 0;
  }
  100% {
    transform: scale(0);
    opacity: 0;
  }
}
.page {
  padding: 24px 24px 0;
}

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

@media (prefers-reduced-motion: reduce) {
  .head__dot {
    transition: none;
    animation: none !important;
  }
  .head.is-scrolled .head__dot {
    transform: scale(1);
    opacity: 1;
  }
  .head.is-demo .head__dot {
    animation: none !important;
    transform: scale(1);
    opacity: 1;
  }
}

// 실제 페이지: 스크롤을 80px 넘게 내리는 순간 알림 점이 튀어나오듯 나타난다 (7줄)
var head = document.querySelector('.head');
window.addEventListener('scroll', function () {
  head.classList.toggle('is-scrolled', window.scrollY > 80);
}, { passive: true });

import { useEffect, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./NoticeHeader.module.scss";

export type NoticeHeaderProps = {
  logo: string;
  /** 이 값(px)을 넘게 스크롤하면 점이 나타난다 (기본 80) */
  threshold?: number;
  /** 점이 튀어나오는 시간 (기본 220ms) */
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function NoticeHeader({
  logo,
  threshold = 80,
  duration = 220,
  easing = "cubic-bezier(.2, 1.4, .4, 1)",
  color = "#2f6df6",
}: NoticeHeaderProps) {
  const [active, setActive] = useState(false);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  useEffect(() => {
    function onScroll() {
      setActive(window.scrollY > threshold);
    }
    window.addEventListener("scroll", onScroll, { passive: true });
    return () => window.removeEventListener("scroll", onScroll);
  }, [threshold]);

  return (
    <header className={styles.head} style={vars}>
      <span className={styles.logo}>{logo}</span>
      <span className={styles.icon} aria-hidden="true">
        <span className={active ? `${styles.dot} ${styles.active}` : styles.dot} />
      </span>
    </header>
  );
}