04Card spotlight glow

<main class="stage is-demo">
  <div class="card">
    <span class="thumb" aria-hidden="true"></span>
    <span class="bar bar--lg" aria-hidden="true"></span>
    <span class="bar bar--sm" aria-hidden="true"></span>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;   // 2s — 스포트라이트 한 바퀴
$easing: ease-in-out;
$color: #b36bff;        // 네온 바이올렛

@include stage($stage-ink);

// 등록 없는 커스텀 프로퍼티는 키프레임으로 보간이 안 된다 — 반드시 @property 로 등록한다 (원리 섹션 재료)
@property --x { syntax: '<percentage>'; inherits: false; initial-value: 50%; }
@property --y { syntax: '<percentage>'; inherits: false; initial-value: 50%; }

.card {
  position: relative;
  overflow: hidden;
  box-sizing: border-box;
  width: clamp(200px, 62vmin, 300px);
  aspect-ratio: 4 / 3;
  border-radius: $r-card;
  background: $stage-ink;
  border: 1px solid rgba($stage-paper, .1);
  padding: $sp-4;
  display: flex; flex-direction: column; justify-content: flex-end; gap: $sp-2;
}

.card::before {
  content: '';
  position: absolute; inset: 0;
  background: radial-gradient(circle at var(--x) var(--y), rgba($color, .55), transparent 55%);
  pointer-events: none;
}

.thumb { position: absolute; top: $sp-4; left: $sp-4; right: $sp-4; height: 46%; border-radius: $r-sm; background: rgba($stage-paper, .08); }
.bar { display: block; height: $sp-2; border-radius: $r-xs; background: rgba($stage-paper, .18); }
.bar--lg { width: 65%; }
.bar--sm { width: 40%; }

// --x·--y 만 움직인다 — @property 등록 덕에 keyframes 가 보간할 수 있다
.stage.is-demo .card::before {
  animation: sweep $duration $easing infinite;
}

@keyframes sweep {
  0%   { --x: 18%; --y: 20%; }
  25%  { --x: 85%; --y: 22%; }
  50%  { --x: 78%; --y: 80%; }
  75%  { --x: 20%; --y: 76%; }
  100% { --x: 18%; --y: 20%; }
}

@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .card::before { animation: none; --x: 50%; --y: 50%; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

@property --x {
  syntax: "<percentage>";
  inherits: false;
  initial-value: 50%;
}
@property --y {
  syntax: "<percentage>";
  inherits: false;
  initial-value: 50%;
}
.card {
  position: relative;
  overflow: hidden;
  box-sizing: border-box;
  width: clamp(200px, 62vmin, 300px);
  aspect-ratio: 4/3;
  border-radius: 16px;
  background: #17141a;
  border: 1px solid rgba(255, 255, 255, 0.1);
  padding: 16px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: 8px;
}

.card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at var(--x) var(--y), rgba(179, 107, 255, 0.55), transparent 55%);
  pointer-events: none;
}

.thumb {
  position: absolute;
  top: 16px;
  left: 16px;
  right: 16px;
  height: 46%;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.08);
}

.bar {
  display: block;
  height: 8px;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.18);
}

.bar--lg {
  width: 65%;
}

.bar--sm {
  width: 40%;
}

.stage.is-demo .card::before {
  animation: sweep 2s ease-in-out infinite;
}

@keyframes sweep {
  0% {
    --x: 18%;
    --y: 20%;
  }
  25% {
    --x: 85%;
    --y: 22%;
  }
  50% {
    --x: 78%;
    --y: 80%;
  }
  75% {
    --x: 20%;
    --y: 76%;
  }
  100% {
    --x: 18%;
    --y: 20%;
  }
}
@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .card::before {
    animation: none;
    --x: 50%;
    --y: 50%;
  }
}

// 실제 커서가 카드 위를 지나가면 --x·--y 를 좌표로 갱신하고 데모 루프를 뗀다 (8줄).
(function () {
  var card = document.querySelector('.card');
  card.addEventListener('pointermove', function (e) {
    var r = card.getBoundingClientRect();
    card.style.setProperty('--x', ((e.clientX - r.left) / r.width * 100) + '%');
    card.style.setProperty('--y', ((e.clientY - r.top) / r.height * 100) + '%');
    document.querySelector('.stage').classList.remove('is-demo');
  });
})();

import { useCallback, useRef } from "react";
import type { CSSProperties, PointerEvent } from "react";
import styles from "./CardSpotlightGlow.module.scss";

export type CardSpotlightGlowProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

export default function CardSpotlightGlow({
  duration = 2000,
  easing = "ease-in-out",
  color = "#b36bff",
}: CardSpotlightGlowProps) {
  const cardRef = useRef<HTMLDivElement | null>(null);

  const onPointerMove = useCallback((e: PointerEvent<HTMLDivElement>) => {
    const el = cardRef.current;
    if (!el) return;
    const r = el.getBoundingClientRect();
    el.style.setProperty("--x", `${((e.clientX - r.left) / r.width) * 100}%`);
    el.style.setProperty("--y", `${((e.clientY - r.top) / r.height) * 100}%`);
  }, []);

  const vars: CSSProperties = { "--duration": `${duration}ms`, "--easing": easing, "--color": color } as CSSProperties;

  return (
    <div ref={cardRef} className={styles.card} style={vars} onPointerMove={onPointerMove}>
      <span className={styles.thumb} aria-hidden="true" />
      <span className={`${styles.bar} ${styles.barLg}`} />
      <span className={`${styles.bar} ${styles.barSm}`} />
    </div>
  );
}