09Neighboring tile glow

<main class="stage">
  <div class="sl-grid is-demo">
    <div class="sl-tile"><span class="sl-tile__tag">Product</span></div>
    <div class="sl-tile"><span class="sl-tile__tag">Design</span></div>
    <div class="sl-tile"><span class="sl-tile__tag">Growth</span></div>
    <div class="sl-tile"><span class="sl-tile__tag">Support</span></div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;
$easing: linear;
$color: $subject-blue;

@include stage($stage-ink);

// 커서 좌표 — 퍼센트 타입으로 등록해야 is-demo 의 키프레임이 값을 보간한다. 그리드 전체에 상속돼 타일마다 같은 지점을 읽는다
@property --mx { syntax: '<percentage>'; inherits: true; initial-value: 50%; }
@property --my { syntax: '<percentage>'; inherits: true; initial-value: 50%; }

.sl-grid {
  width: min(320px, 88vw);
  aspect-ratio: 340 / 190;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  grid-template-rows: repeat(2, 1fr);
  gap: $sp-2;
  --mx: 50%;
  --my: 50%;
}

.sl-tile {
  border-radius: $r-sm;
  padding: $sp-3;
  box-sizing: border-box;
  color: $subject-cream;
  background: $subject-ink;
  font: 600 12px/1 -apple-system, "Segoe UI", sans-serif;
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: flex-end;
}
.sl-tile__tag { position: relative; z-index: 1; opacity: .85; }

// 글로우 레이어 — 좌표는 공유하지만 opacity 는 :has() 로 "그리드 안 어딘가 호버 중"일 때만 켠다
.sl-tile::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(140px circle at var(--mx) var(--my), rgba($color, .6), transparent 70%);
  opacity: 0;
  transition: opacity 200ms $easing;
  pointer-events: none;
}

// 실사용: 진짜 pointermove 가 --mx·--my 를 갱신한다(위 <script>). 호버 중인 타일이 그리드 안에 있으면 전부 켠다
.sl-grid:has(.sl-tile:hover) .sl-tile::before { opacity: 1; }

// 데모 루프: is-demo 는 :has(:hover) 를 못 거니 opacity 를 직접 켜고, --mx·--my 는 keyframes 로 원을 그리며 돈다(캡처용)
@keyframes sl-drift {
  0%   { --mx: 10%; --my: 15%; }
  25%  { --mx: 90%; --my: 10%; }
  50%  { --mx: 85%; --my: 90%; }
  75%  { --mx: 10%; --my: 85%; }
  100% { --mx: 10%; --my: 15%; }
}
.sl-grid.is-demo { animation: sl-drift $duration $easing infinite; }
.sl-grid.is-demo .sl-tile::before { opacity: 1; }

@media (prefers-reduced-motion: reduce) {
  .sl-grid.is-demo { animation: none !important; }
  .sl-tile::before { transition: none !important; }
}

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 --mx {
  syntax: "<percentage>";
  inherits: true;
  initial-value: 50%;
}
@property --my {
  syntax: "<percentage>";
  inherits: true;
  initial-value: 50%;
}
.sl-grid {
  width: min(320px, 88vw);
  aspect-ratio: 340/190;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  grid-template-rows: repeat(2, 1fr);
  gap: 8px;
  --mx: 50%;
  --my: 50%;
}

.sl-tile {
  border-radius: 8px;
  padding: 12px;
  box-sizing: border-box;
  color: #fff7e6;
  background: #17141a;
  font: 600 12px/1 -apple-system, "Segoe UI", sans-serif;
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: flex-end;
}

.sl-tile__tag {
  position: relative;
  z-index: 1;
  opacity: 0.85;
}

.sl-tile::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(140px circle at var(--mx) var(--my), rgba(47, 109, 246, 0.6), transparent 70%);
  opacity: 0;
  transition: opacity 200ms linear;
  pointer-events: none;
}

.sl-grid:has(.sl-tile:hover) .sl-tile::before {
  opacity: 1;
}

@keyframes sl-drift {
  0% {
    --mx: 10%;
    --my: 15%;
  }
  25% {
    --mx: 90%;
    --my: 10%;
  }
  50% {
    --mx: 85%;
    --my: 90%;
  }
  75% {
    --mx: 10%;
    --my: 85%;
  }
  100% {
    --mx: 10%;
    --my: 15%;
  }
}
.sl-grid.is-demo {
  animation: sl-drift 2s linear infinite;
}

.sl-grid.is-demo .sl-tile::before {
  opacity: 1;
}

@media (prefers-reduced-motion: reduce) {
  .sl-grid.is-demo {
    animation: none !important;
  }
  .sl-tile::before {
    transition: none !important;
  }
}

var grid = document.querySelector('.sl-grid');
grid.addEventListener('pointermove', function (e) {
  var r = grid.getBoundingClientRect();
  var x = ((e.clientX - r.left) / r.width * 100).toFixed(1) + '%';
  var y = ((e.clientY - r.top) / r.height * 100).toFixed(1) + '%';
  grid.style.setProperty('--mx', x);
  grid.style.setProperty('--my', y);
});

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

type Vars = CSSProperties & { "--color"?: string; "--mx"?: string; "--my"?: string };

export interface SpotlightNeighborsProps {
  color?: string;
}

const LABELS = ["Product", "Design", "Growth", "Support"];

// 실사용: 진짜 pointermove 로 --mx·--my 를 갱신한다. 켜고 끄는 건 CSS :has() 가 한다
export default function SpotlightNeighbors({ color = "#2f6df6" }: SpotlightNeighborsProps) {
  const gridRef = useRef<HTMLDivElement>(null);

  const handleMove = useCallback((e: PointerEvent<HTMLDivElement>) => {
    const el = gridRef.current;
    if (!el) return;
    const r = el.getBoundingClientRect();
    const x = (((e.clientX - r.left) / r.width) * 100).toFixed(1) + "%";
    const y = (((e.clientY - r.top) / r.height) * 100).toFixed(1) + "%";
    el.style.setProperty("--mx", x);
    el.style.setProperty("--my", y);
  }, []);

  const style: Vars = { "--color": color };

  return (
    <div className={styles.grid} style={style} ref={gridRef} onPointerMove={handleMove}>
      {LABELS.map((label) => (
        <div key={label} className={styles.tile}>
          <span className={styles.tag}>{label}</span>
        </div>
      ))}
    </div>
  );
}