03Sparkle button

<main class="stage">
  <div class="sk-wrap is-demo">
    <button class="sk-btn" type="button">Upgrade to Premium</button>
    <span class="sk-star sk-star--1">✦</span>
    <span class="sk-star sk-star--2">✦</span>
    <span class="sk-star sk-star--3">✦</span>
    <span class="sk-star sk-star--4">✦</span>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: 1.1s;
$easing: $ease-out;
$color: $stage-yellow;

@include stage($stage-orange);

.sk-wrap {
  position: relative;
  width: min(240px, 82vw);
  display: grid;
  place-items: center;
}

.sk-btn {
  position: relative;
  z-index: 1;
  border: 0;
  border-radius: $r-control;
  padding: $sp-3 $sp-6;
  background: $subject-ink;
  color: $subject-cream;
  font: 700 14px/1 -apple-system, "Segoe UI", sans-serif;
  cursor: pointer;
  transition: transform $dur-quick $easing;
}
.sk-wrap:hover .sk-btn { transform: scale(1.03); }

.sk-star {
  position: absolute;
  color: $color;
  font-size: 16px;
  line-height: 1;
  opacity: 0;
  transform: scale(.3);
  pointer-events: none;
}
.sk-star--1 { top: -6px;  left: 6%; }
.sk-star--2 { top: -14px; right: 10%; }
.sk-star--3 { bottom: -10px; left: 16%; }
.sk-star--4 { bottom: -4px; right: 4%; }

@keyframes sk-twinkle {
  0%, 100% { opacity: 0; transform: scale(.3) rotate(0deg); }
  50%      { opacity: 1; transform: scale(1) rotate(90deg); }
}

// 실사용: 호버 중에만 반짝인다. 캡처용 is-demo 는 항상 켠다
.sk-wrap:hover .sk-star,
.sk-wrap.is-demo .sk-star { animation: sk-twinkle $duration $easing infinite; }
.sk-star--2 { animation-delay: 160ms; }
.sk-star--3 { animation-delay: 320ms; }
.sk-star--4 { animation-delay: 480ms; }

@media (prefers-reduced-motion: reduce) {
  .sk-wrap:hover .sk-star,
  .sk-wrap.is-demo .sk-star { animation: none !important; opacity: 0 !important; }
}

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);
}

.sk-wrap {
  position: relative;
  width: min(240px, 82vw);
  display: grid;
  place-items: center;
}

.sk-btn {
  position: relative;
  z-index: 1;
  border: 0;
  border-radius: 12px;
  padding: 12px 24px;
  background: #17141a;
  color: #fff7e6;
  font: 700 14px/1 -apple-system, "Segoe UI", sans-serif;
  cursor: pointer;
  transition: transform 220ms ease-out;
}

.sk-wrap:hover .sk-btn {
  transform: scale(1.03);
}

.sk-star {
  position: absolute;
  color: #ffd23f;
  font-size: 16px;
  line-height: 1;
  opacity: 0;
  transform: scale(0.3);
  pointer-events: none;
}

.sk-star--1 {
  top: -6px;
  left: 6%;
}

.sk-star--2 {
  top: -14px;
  right: 10%;
}

.sk-star--3 {
  bottom: -10px;
  left: 16%;
}

.sk-star--4 {
  bottom: -4px;
  right: 4%;
}

@keyframes sk-twinkle {
  0%, 100% {
    opacity: 0;
    transform: scale(0.3) rotate(0deg);
  }
  50% {
    opacity: 1;
    transform: scale(1) rotate(90deg);
  }
}
.sk-wrap:hover .sk-star,
.sk-wrap.is-demo .sk-star {
  animation: sk-twinkle 1.1s ease-out infinite;
}

.sk-star--2 {
  animation-delay: 160ms;
}

.sk-star--3 {
  animation-delay: 320ms;
}

.sk-star--4 {
  animation-delay: 480ms;
}

@media (prefers-reduced-motion: reduce) {
  .sk-wrap:hover .sk-star,
  .sk-wrap.is-demo .sk-star {
    animation: none !important;
    opacity: 0 !important;
  }
}

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

type Vars = CSSProperties & Record<string, string>;

export interface SparkleButtonProps {
  duration?: string;
  easing?: string;
  color?: string;
}

// 실사용: 진짜 :hover 중에만 반짝인다 (module.scss 의 .wrap:hover). props 는 변수 3개만 넘긴다
export default function SparkleButton({
  duration = "1.1s",
  easing = "ease-out",
  color = "#ffd23f",
}: SparkleButtonProps) {
  const style: Vars = { "--duration": duration, "--easing": easing, "--color": color };
  return (
    <div className={styles.wrap} style={style}>
      <button className={styles.btn} type="button">
        프리미엄 업그레이드
      </button>
      <span className={`${styles.star} ${styles.star1}`}>✦</span>
      <span className={`${styles.star} ${styles.star2}`}>✦</span>
      <span className={`${styles.star} ${styles.star3}`}>✦</span>
      <span className={`${styles.star} ${styles.star4}`}>✦</span>
    </div>
  );
}