css 버튼 입체감 9가지 — 클릭 효과까지 커스텀 코드

<main class="stage">
<div class="cr is-demo" id="cr">
  <p class="cr__hint"><span>커서를 버튼 위에서 움직이면 좌표 값이 rotateX·rotateY 를 계산합니다</span></p>
  <div class="cr__scene" id="scene">
    <button class="cr__btn" id="btn" type="button" aria-label="지금 시작하기 — 커서를 따라 기울어지는 버튼">
      <span class="cr__sheen" id="sheen" aria-hidden="true"></span>
      <span class="cr__label">지금 시작하기</span>
    </button>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-ink);

.cr {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.cr__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba($subject-cream, .78);
}

.cr__scene {
  perspective: 640px;
  padding: $sp-6;
}

.cr__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: $sp-4 $sp-8;
  border-radius: $r-control;
  background: $subject-blue-deep;
  color: $subject-cream;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: .01em;
  transform-style: preserve-3d;
  box-shadow: $shadow-raised;
  overflow: hidden;
  will-change: transform;
}

.cr__btn:focus-visible {
  outline: 2px solid $subject-cream;
  outline-offset: 3px;
}

.cr__sheen {
  position: absolute;
  inset: 0;
  pointer-events: none;
  mix-blend-mode: soft-light;
}

.cr__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .cr__btn { transition: none; }
}

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);
}

.cr {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.cr__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba(255, 247, 230, 0.78);
}

.cr__scene {
  perspective: 640px;
  padding: 24px;
}

.cr__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: 16px 32px;
  border-radius: 12px;
  background: #0a4fe8;
  color: #fff7e6;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.01em;
  transform-style: preserve-3d;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  overflow: hidden;
  will-change: transform;
}

.cr__btn:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 3px;
}

.cr__sheen {
  position: absolute;
  inset: 0;
  pointer-events: none;
  mix-blend-mode: soft-light;
}

.cr__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .cr__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('cr');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var sheen = document.getElementById('sheen');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var MAX_DEG = 14;          // 커서가 버튼 가장자리에 닿았을 때의 최대 회전각
  var LERP = 0.16;           // 관성 lerp 계수 — 값이 목표를 따라잡는 속도
  var targetNX = 0, targetNY = 0;
  var curNX = 0, curNY = 0;
  var hasPointer = false;
  var clickTimer = null;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }

  // 포인터가 없을 때(자동 시연·헤드리스 측정) 같은 계산을 돌리기 위한 합성 좌표 — 두 축의 위상을 어긋낸 리사주 궤적
  function syntheticTarget(t) {
    return [Math.sin(t * 1.15), Math.sin(t * 0.82 + 1.05)];
  }

  function render(nx, ny) {
    var rotY = nx * MAX_DEG;
    var rotX = -ny * MAX_DEG;
    btn.style.transform = 'rotateX(' + rotX.toFixed(2) + 'deg) rotateY(' + rotY.toFixed(2) + 'deg)';
    var sx = 50 + nx * 34, sy = 50 + ny * 34;
    sheen.style.background = 'radial-gradient(circle at ' + sx.toFixed(1) + '% ' + sy.toFixed(1) + '%, rgba(255,247,230,.5), rgba(255,247,230,0) 58%)';
    var depth = Math.min(1, Math.sqrt(nx * nx + ny * ny));
    btn.style.boxShadow = '0 ' + (10 + depth * 16).toFixed(1) + 'px ' + (18 + depth * 22).toFixed(1) + 'px rgba(8,6,12,' + (0.30 + depth * 0.16).toFixed(2) + ')';
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) { t0 = now; }
    var t = (now - t0) / 1000;
    if (!hasPointer && !reduce) {
      var s = syntheticTarget(t);
      targetNX = s[0]; targetNY = s[1];
    }
    curNX += (targetNX - curNX) * LERP;
    curNY += (targetNY - curNY) * LERP;
    render(curNX, curNY);
    requestAnimationFrame(loop);
  }

  function pointFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var nx = ((e.clientX - r.left) / r.width) * 2 - 1;
    var ny = ((e.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var p = pointFromEvent(e);
    targetNX = p[0]; targetNY = p[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
    targetNX = 0; targetNY = 0;
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = 0.92; targetNY = -0.62;
    if (reduce) { render(targetNX, targetNY); }
    clearTimeout(clickTimer);
    clickTimer = setTimeout(function () { hasPointer = false; targetNX = 0; targetNY = 0; if (reduce) { render(targetNX, targetNY); } }, 260);
  });
  btn.addEventListener('keydown', function (e) {
    var step = 0.24;
    var moves = { ArrowLeft: [-step, 0], ArrowRight: [step, 0], ArrowUp: [0, -step], ArrowDown: [0, step] };
    var m = moves[e.key];
    if (!m) { return; }
    e.preventDefault();
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = clamp(targetNX + m[0], -1, 1);
    targetNY = clamp(targetNY + m[1], -1, 1);
    if (reduce) { render(targetNX, targetNY); }
  });

  if (reduce) {
    render(0.5, -0.34);
  } else {
    requestAnimationFrame(loop);
  }
})();

// CursorRotateButton — vanilla 판(run/393/demo/01-pointer-tilt-3d-cursor-rotate/index.html) 의 React 포트.
// 버튼 안 커서 좌표를 -1~1 로 정규화해 목표값(target)을 만들고, 관성 lerp 로 현재값(cur)이 따라간다.
// 포인터가 없을 때(자동 시연)는 위상이 어긋난 두 사인파(리사주 궤적)를 목표값으로 써 같은 계산을 돌린다.
// 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./CursorRotateButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const MAX_DEG = 14;
const LERP = 0.16;
const LABEL = "지금 시작하기 — 커서를 따라 기울어지는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}

function syntheticTarget(t: number): [number, number] {
  return [Math.sin(t * 1.15), Math.sin(t * 0.82 + 1.05)];
}

export default function CursorRotateButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const sheenRef = useRef<HTMLSpanElement | null>(null);
  const targetXRef = useRef<number>(0) as Box<number>;
  const targetYRef = useRef<number>(0) as Box<number>;
  const curXRef = useRef<number>(0) as Box<number>;
  const curYRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const clickTimerRef = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(nx: number, ny: number): void {
    const btn = btnRef.current;
    const sheen = sheenRef.current;
    if (!btn || !sheen) return;
    const rotY = nx * MAX_DEG;
    const rotX = -ny * MAX_DEG;
    btn.style.transform = "rotateX(" + rotX.toFixed(2) + "deg) rotateY(" + rotY.toFixed(2) + "deg)";
    const sx = 50 + nx * 34;
    const sy = 50 + ny * 34;
    sheen.style.background =
      "radial-gradient(circle at " + sx.toFixed(1) + "% " + sy.toFixed(1) + "%, rgba(255,247,230,.5), rgba(255,247,230,0) 58%)";
    const depth = Math.min(1, Math.sqrt(nx * nx + ny * ny));
    btn.style.boxShadow =
      "0 " + (10 + depth * 16).toFixed(1) + "px " + (18 + depth * 22).toFixed(1) + "px rgba(8,6,12," + (0.3 + depth * 0.16).toFixed(2) + ")";
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(0.5, -0.34);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      if (!hasPointerRef.current) {
        const s = syntheticTarget(t);
        targetXRef.current = s[0];
        targetYRef.current = s[1];
      }
      curXRef.current += (targetXRef.current - curXRef.current) * LERP;
      curYRef.current += (targetYRef.current - curYRef.current) * LERP;
      render(curXRef.current, curYRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function pointFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const nx = ((event.clientX - r.left) / r.width) * 2 - 1;
    const ny = ((event.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const p = pointFromEvent(event);
    targetXRef.current = p[0];
    targetYRef.current = p[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
    targetXRef.current = 0;
    targetYRef.current = 0;
  }

  function onClick(): void {
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = 0.92;
    targetYRef.current = -0.62;
    if (reduce) render(targetXRef.current, targetYRef.current);
    window.clearTimeout(clickTimerRef.current);
    clickTimerRef.current = window.setTimeout(() => {
      hasPointerRef.current = false;
      targetXRef.current = 0;
      targetYRef.current = 0;
      if (reduce) render(targetXRef.current, targetYRef.current);
    }, 260);
  }

  function onKeyDown(event: KeyEvt): void {
    const step = 0.24;
    const moves: { [key: string]: [number, number] } = {
      ArrowLeft: [-step, 0],
      ArrowRight: [step, 0],
      ArrowUp: [0, -step],
      ArrowDown: [0, step],
    };
    const m = moves[event.key];
    if (!m) return;
    event.preventDefault();
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = clamp(targetXRef.current + m[0], -1, 1);
    targetYRef.current = clamp(targetYRef.current + m[1], -1, 1);
    if (reduce) render(targetXRef.current, targetYRef.current);
  }

  const cls = [styles.cr, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>커서를 버튼 위에서 움직이면 좌표 값이 rotateX·rotateY 를 계산합니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <button className={styles.btn} ref={btnRef} type="button" aria-label={LABEL} onClick={onClick} onKeyDown={onKeyDown}>
            <span className={styles.sheen} ref={sheenRef} aria-hidden="true" />
            <span className={styles.label}>지금 시작하기</span>
          </button>
        </div>
      </div>
    </main>
  );
}

<main class="stage">
<div class="ss is-demo" id="ss">
  <p class="ss__hint"><span>포인터 각도를 계산해 광택 줄기가 그 방향으로 흐릅니다</span></p>
  <div class="ss__scene" id="scene">
    <span class="ss__glow" id="glow" aria-hidden="true"></span>
    <span class="ss__floor" id="floor" aria-hidden="true"></span>
    <button class="ss__btn" id="btn" type="button" aria-label="프리미엄 결제 — 포인터 각도로 광택이 흐르는 버튼">
      <span class="ss__sweep" id="sweep" aria-hidden="true"></span>
      <span class="ss__label">프리미엄 결제</span>
    </button>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-yellow);

.ss {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.ss__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba($subject-ink, .78);
}

.ss__scene {
  position: relative;
  perspective: 640px;
  padding: $sp-6;
}

.ss__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: $sp-6 $sp-12;
  border-radius: $r-control;
  background: $subject-ink;
  color: $subject-cream;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: $shadow-raised;
  overflow: hidden;
  will-change: transform;
}

.ss__btn:focus-visible {
  outline: 2px solid $subject-ink;
  outline-offset: 3px;
}

.ss__sweep {
  position: absolute;
  inset: -58%;
  pointer-events: none;
}

// 배경 반사광 — 각도·세기에 따라 위치만 이동(% 좌표, transform 없음 → 폭 넘침 없음)
.ss__glow {
  position: absolute;
  inset: 0;
  border-radius: inherit;
  pointer-events: none;
  z-index: 0;
}

// 기울기에 연동된 바닥 그림자 — 버튼 면적만으로는 안 보이던 움직임을 면으로 키운다
.ss__floor {
  position: absolute;
  left: 50%;
  bottom: 2px;
  width: clamp(150px, 58vw, 280px);
  height: clamp(48px, 18.6vw, 90px);
  margin-left: clamp(-140px, -29vw, -75px);
  border-radius: 50%;
  background: radial-gradient(closest-side, rgba($subject-ink, .92), rgba($subject-ink, 0) 72%);
  filter: blur(6px);
  pointer-events: none;
}

.ss__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .ss__btn { transition: none; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.ss {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.ss__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba(23, 20, 26, 0.78);
}

.ss__scene {
  position: relative;
  perspective: 640px;
  padding: 24px;
}

.ss__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: 24px 48px;
  border-radius: 12px;
  background: #17141a;
  color: #fff7e6;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  overflow: hidden;
  will-change: transform;
}

.ss__btn:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: 3px;
}

.ss__sweep {
  position: absolute;
  inset: -58%;
  pointer-events: none;
}

.ss__glow {
  position: absolute;
  inset: 0;
  border-radius: inherit;
  pointer-events: none;
  z-index: 0;
}

.ss__floor {
  position: absolute;
  left: 50%;
  bottom: 2px;
  width: clamp(150px, 58vw, 280px);
  height: clamp(48px, 18.6vw, 90px);
  margin-left: clamp(-140px, -29vw, -75px);
  border-radius: 50%;
  background: radial-gradient(closest-side, rgba(23, 20, 26, 0.92), rgba(23, 20, 26, 0) 72%);
  filter: blur(6px);
  pointer-events: none;
}

.ss__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .ss__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('ss');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var sweep = document.getElementById('sweep');
  var floor = document.getElementById('floor');
  var glow = document.getElementById('glow');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var SWEEP_WIDTH = 46;      // 광택 줄기의 각도 폭(deg) — 불변
  var LERP = 0.2;
  var targetAngle = 0, curAngle = 0;
  var targetMag = 0, curMag = 0;
  var hasPointer = false;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }

  // 합성 포인터 각도 — 원을 그리며 도는 위상(자동 시연 · 헤드리스 측정)
  // 진폭을 넓혀 자동 시연에서도 기울기가 가장자리(최대 각)까지 실제로 닿게 한다(경로 상수만 조정)
  function syntheticAngle(t) { return t * 74; }
  function syntheticMag(t) { return Math.min(1, 0.6 + 0.55 * Math.sin(t * 1.3)); }

  function shortestDelta(from, to) {
    var d = (to - from) % 360;
    if (d > 180) d -= 360;
    if (d < -180) d += 360;
    return d;
  }

  function render(angle, mag) {
    var rotY = Math.cos(angle * Math.PI / 180) * mag * 10;
    var rotX = Math.sin(angle * Math.PI / 180) * mag * -10;
    btn.style.transform = 'rotateX(' + rotX.toFixed(2) + 'deg) rotateY(' + rotY.toFixed(2) + 'deg)';
    var a0 = (angle - SWEEP_WIDTH / 2).toFixed(1);
    var a1 = angle.toFixed(1);
    var a2 = (angle + SWEEP_WIDTH / 2).toFixed(1);
    // 대비·폭(요소 크기)을 키워 광택 줄기가 버튼 면 전체를 가로지르게 — SWEEP_WIDTH(각도 폭) 값 자체는 그대로
    var alpha = (0.46 + mag * 0.54).toFixed(2);
    sweep.style.background = 'conic-gradient(from ' + a0 + 'deg at 50% 50%, rgba(23,20,26,0), rgba(23,20,26,' + alpha + ') ' + (SWEEP_WIDTH / 2).toFixed(1) + 'deg, rgba(23,20,26,0) ' + SWEEP_WIDTH.toFixed(1) + 'deg)';
    sweep.style.opacity = String(0.8 + mag * 0.4);
    // 기울기에 연동된 바닥 그림자 — 버튼이 기운 방향으로 그림자가 옮겨가며 면적을 만든다
    var floorShift = Math.cos(angle * Math.PI / 180) * mag * 34;
    var floorScale = 1 + mag * 0.28;
    floor.style.transform = 'translateX(' + floorShift.toFixed(1) + 'px) scaleX(' + floorScale.toFixed(2) + ')';
    floor.style.opacity = (0.08 + mag * 0.88).toFixed(2);
    // 배경에 반사광 레이어 — % 좌표만 써서 이동시키므로 폭 넘침 위험이 없다(transform 미사용)
    var gx = (50 + Math.cos(angle * Math.PI / 180) * mag * 38).toFixed(0);
    var gy = (50 + Math.sin(angle * Math.PI / 180) * mag * 38).toFixed(0);
    glow.style.background = 'radial-gradient(circle at ' + gx + '% ' + gy + '%, rgba(255,255,255,' + (0.18 + mag * 0.5).toFixed(2) + '), rgba(255,255,255,0) 60%)';
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) t0 = now;
    var t = (now - t0) / 1000;
    if (!hasPointer && !reduce) {
      targetAngle = syntheticAngle(t) % 360;
      targetMag = syntheticMag(t);
    }
    curAngle += shortestDelta(curAngle, targetAngle) * LERP;
    curMag += (targetMag - curMag) * LERP;
    render(curAngle, curMag);
    requestAnimationFrame(loop);
  }

  function angleFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var cx = r.left + r.width / 2, cy = r.top + r.height / 2;
    var dx = e.clientX - cx, dy = e.clientY - cy;
    var ang = Math.atan2(dy, dx) * 180 / Math.PI;
    var mag = clamp(Math.sqrt(dx * dx + dy * dy) / (r.width / 2), 0, 1);
    return [ang, mag];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var a = angleFromEvent(e);
    targetAngle = a[0]; targetMag = a[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
    targetMag = 0.15;
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    targetMag = 1;
    if (reduce) { render(targetAngle, targetMag); }
    setTimeout(function () { targetMag = hasPointer ? 0.5 : 0.15; if (reduce) { render(targetAngle, targetMag); } }, 220);
  });
  btn.addEventListener('keydown', function (e) {
    var step = 18;
    if (e.key === 'ArrowLeft') { e.preventDefault(); root.classList.remove('is-demo'); hasPointer = true; targetAngle -= step; }
    else if (e.key === 'ArrowRight') { e.preventDefault(); root.classList.remove('is-demo'); hasPointer = true; targetAngle += step; }
    else { return; }
    if (reduce) { render(targetAngle, targetMag); }
  });

  if (reduce) {
    render(45, 0.4);
  } else {
    requestAnimationFrame(loop);
  }
})();

// SpecularSweepButton — vanilla 판(run/393/demo/02-pointer-tilt-3d-specular-sweep/index.html) 의 React 포트.
// 포인터와 중심의 각도(atan2)·거리 비율을 계산해 conic-gradient 광택 줄기의 각도·세기로 바꾼다.
// 각도는 최단 경로(shortest delta)로 lerp 해 360→0 경계에서 튀지 않는다. 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./SpecularSweepButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const SWEEP_WIDTH = 46; // 불변
const LERP = 0.2;
const LABEL = "프리미엄 결제 — 포인터 각도로 광택이 흐르는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}
function syntheticAngle(t: number): number {
  return t * 74;
}
// 진폭을 넓혀 자동 시연에서도 기울기가 가장자리(최대 각)까지 실제로 닿게 한다(경로 상수만 조정)
function syntheticMag(t: number): number {
  return Math.min(1, 0.6 + 0.55 * Math.sin(t * 1.3));
}
function shortestDelta(from: number, to: number): number {
  let d = (to - from) % 360;
  if (d > 180) d -= 360;
  if (d < -180) d += 360;
  return d;
}

export default function SpecularSweepButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const sweepRef = useRef<HTMLSpanElement | null>(null);
  const floorRef = useRef<HTMLSpanElement | null>(null);
  const glowRef = useRef<HTMLSpanElement | null>(null);
  const targetAngleRef = useRef<number>(0) as Box<number>;
  const curAngleRef = useRef<number>(0) as Box<number>;
  const targetMagRef = useRef<number>(0) as Box<number>;
  const curMagRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const clickTimerRef = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(angle: number, mag: number): void {
    const btn = btnRef.current;
    const sweep = sweepRef.current;
    const floor = floorRef.current;
    const glow = glowRef.current;
    if (!btn || !sweep || !floor || !glow) return;
    const rotY = Math.cos((angle * Math.PI) / 180) * mag * 10;
    const rotX = Math.sin((angle * Math.PI) / 180) * mag * -10;
    btn.style.transform = "rotateX(" + rotX.toFixed(2) + "deg) rotateY(" + rotY.toFixed(2) + "deg)";
    const a0 = (angle - SWEEP_WIDTH / 2).toFixed(1);
    const alpha = (0.46 + mag * 0.54).toFixed(2);
    sweep.style.background =
      "conic-gradient(from " + a0 + "deg at 50% 50%, rgba(23,20,26,0), rgba(23,20,26," + alpha + ") " + (SWEEP_WIDTH / 2).toFixed(1) + "deg, rgba(23,20,26,0) " + SWEEP_WIDTH.toFixed(1) + "deg)";
    sweep.style.opacity = String(0.8 + mag * 0.4);
    const floorShift = Math.cos((angle * Math.PI) / 180) * mag * 34;
    const floorScale = 1 + mag * 0.28;
    floor.style.transform = "translateX(" + floorShift.toFixed(1) + "px) scaleX(" + floorScale.toFixed(2) + ")";
    floor.style.opacity = (0.08 + mag * 0.88).toFixed(2);
    const gx = (50 + Math.cos((angle * Math.PI) / 180) * mag * 38).toFixed(0);
    const gy = (50 + Math.sin((angle * Math.PI) / 180) * mag * 38).toFixed(0);
    glow.style.background = "radial-gradient(circle at " + gx + "% " + gy + "%, rgba(255,255,255," + (0.18 + mag * 0.5).toFixed(2) + "), rgba(255,255,255,0) 60%)";
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(45, 0.4);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      if (!hasPointerRef.current) {
        targetAngleRef.current = syntheticAngle(t) % 360;
        targetMagRef.current = syntheticMag(t);
      }
      curAngleRef.current += shortestDelta(curAngleRef.current, targetAngleRef.current) * LERP;
      curMagRef.current += (targetMagRef.current - curMagRef.current) * LERP;
      render(curAngleRef.current, curMagRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function angleFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const cx = r.left + r.width / 2;
    const cy = r.top + r.height / 2;
    const dx = event.clientX - cx;
    const dy = event.clientY - cy;
    const ang = (Math.atan2(dy, dx) * 180) / Math.PI;
    const mag = clamp(Math.sqrt(dx * dx + dy * dy) / (r.width / 2), 0, 1);
    return [ang, mag];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const a = angleFromEvent(event);
    targetAngleRef.current = a[0];
    targetMagRef.current = a[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
    targetMagRef.current = 0.15;
  }

  function onClick(): void {
    setDemo(false);
    hasPointerRef.current = true;
    targetMagRef.current = 1;
    if (reduce) render(targetAngleRef.current, targetMagRef.current);
    window.clearTimeout(clickTimerRef.current);
    clickTimerRef.current = window.setTimeout(() => {
      targetMagRef.current = hasPointerRef.current ? 0.5 : 0.15;
      if (reduce) render(targetAngleRef.current, targetMagRef.current);
    }, 220);
  }

  function onKeyDown(event: KeyEvt): void {
    const step = 18;
    if (event.key === "ArrowLeft") {
      event.preventDefault();
      setDemo(false);
      hasPointerRef.current = true;
      targetAngleRef.current -= step;
    } else if (event.key === "ArrowRight") {
      event.preventDefault();
      setDemo(false);
      hasPointerRef.current = true;
      targetAngleRef.current += step;
    } else {
      return;
    }
    if (reduce) render(targetAngleRef.current, targetMagRef.current);
  }

  const cls = [styles.ss, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>포인터 각도를 계산해 광택 줄기가 그 방향으로 흐릅니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <span className={styles.glow} ref={glowRef} aria-hidden="true" />
          <span className={styles.floor} ref={floorRef} aria-hidden="true" />
          <button className={styles.btn} ref={btnRef} type="button" aria-label={LABEL} onClick={onClick} onKeyDown={onKeyDown}>
            <span className={styles.sweep} ref={sweepRef} aria-hidden="true" />
            <span className={styles.label}>프리미엄 결제</span>
          </button>
        </div>
      </div>
    </main>
  );
}

<main class="stage">
<div class="sk is-demo" id="sk">
  <p class="sk__hint"><span>기운 방향의 반대쪽으로 그림자 세 겹이 어긋나 쌓입니다</span></p>
  <div class="sk__scene" id="scene">
    <button class="sk__btn" id="btn" type="button" aria-label="지금 구매하기 — 기울기에 따라 그림자가 쌓이는 버튼">
      <span class="sk__label">지금 구매하기</span>
    </button>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-orange);

.sk {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.sk__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: $subject-ink;
}

.sk__scene {
  perspective: 640px;
  padding: $sp-6;
}

.sk__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: $sp-4 $sp-8;
  border-radius: $r-control;
  background: $subject-cream;
  color: $subject-ink;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  will-change: transform;
}

.sk__btn:focus-visible {
  outline: 2px solid $subject-ink;
  outline-offset: 3px;
}

.sk__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .sk__btn { transition: none; }
}

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 {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.sk__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: #17141a;
}

.sk__scene {
  perspective: 640px;
  padding: 24px;
}

.sk__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: 16px 32px;
  border-radius: 12px;
  background: #fff7e6;
  color: #17141a;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  will-change: transform;
}

.sk__btn:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: 3px;
}

.sk__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .sk__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('sk');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var MAX_DEG = 12;
  var LERP = 0.15;
  var targetNX = 0, targetNY = 0;
  var curNX = 0, curNY = 0;
  var hasPointer = false;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }
  function syntheticTarget(t) { return [Math.sin(t * 0.95 + 0.4), Math.sin(t * 1.35)]; }

  // 그림자 3겹 — 기운 반대 방향으로 오프셋이 커지고, 층마다 흐림·투명도가 달라 깊이가 읽힌다
  function render(nx, ny) {
    var rotY = nx * MAX_DEG;
    var rotX = -ny * MAX_DEG;
    btn.style.transform = 'rotateX(' + rotX.toFixed(2) + 'deg) rotateY(' + rotY.toFixed(2) + 'deg)';
    var ox = -nx, oy = -ny;
    var layers = [];
    for (var i = 1; i <= 3; i++) {
      var d = i * 7;
      var blur = i * 9;
      var alpha = (0.22 - i * 0.03).toFixed(2);
      layers.push((ox * d).toFixed(1) + 'px ' + (oy * d + i * 3).toFixed(1) + 'px ' + blur + 'px rgba(23,20,26,' + alpha + ')');
    }
    btn.style.boxShadow = layers.join(', ');
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) t0 = now;
    var t = (now - t0) / 1000;
    if (!hasPointer && !reduce) {
      var s = syntheticTarget(t);
      targetNX = s[0]; targetNY = s[1];
    }
    curNX += (targetNX - curNX) * LERP;
    curNY += (targetNY - curNY) * LERP;
    render(curNX, curNY);
    requestAnimationFrame(loop);
  }

  function pointFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var nx = ((e.clientX - r.left) / r.width) * 2 - 1;
    var ny = ((e.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var p = pointFromEvent(e);
    targetNX = p[0]; targetNY = p[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
    targetNX = 0; targetNY = 0;
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = -0.8; targetNY = 0.5;
    if (reduce) { render(targetNX, targetNY); }
    setTimeout(function () { if (!hasPointer) { targetNX = 0; targetNY = 0; if (reduce) { render(targetNX, targetNY); } } }, 240);
  });
  btn.addEventListener('keydown', function (e) {
    var step = 0.22;
    var moves = { ArrowLeft: [-step, 0], ArrowRight: [step, 0], ArrowUp: [0, -step], ArrowDown: [0, step] };
    var m = moves[e.key];
    if (!m) return;
    e.preventDefault();
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = clamp(targetNX + m[0], -1, 1);
    targetNY = clamp(targetNY + m[1], -1, 1);
    if (reduce) { render(targetNX, targetNY); }
  });

  if (reduce) {
    render(-0.4, 0.3);
  } else {
    requestAnimationFrame(loop);
  }
})();

// ShadowStackButton — vanilla 판(run/393/demo/03-pointer-tilt-3d-shadow-stack/index.html) 의 React 포트.
// 정규화된 포인터 좌표의 반대 방향으로 그림자 3겹을 서로 다른 거리·흐림·투명도로 쌓아 깊이를 만든다.
// 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./ShadowStackButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const MAX_DEG = 12;
const LERP = 0.15;
const LABEL = "지금 구매하기 — 기울기에 따라 그림자가 쌓이는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}
function syntheticTarget(t: number): [number, number] {
  return [Math.sin(t * 0.95 + 0.4), Math.sin(t * 1.35)];
}

export default function ShadowStackButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const targetXRef = useRef<number>(0) as Box<number>;
  const targetYRef = useRef<number>(0) as Box<number>;
  const curXRef = useRef<number>(0) as Box<number>;
  const curYRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(nx: number, ny: number): void {
    const btn = btnRef.current;
    if (!btn) return;
    const rotY = nx * MAX_DEG;
    const rotX = -ny * MAX_DEG;
    btn.style.transform = "rotateX(" + rotX.toFixed(2) + "deg) rotateY(" + rotY.toFixed(2) + "deg)";
    const ox = -nx;
    const oy = -ny;
    const layers: string[] = [];
    for (let i = 1; i <= 3; i++) {
      const d = i * 7;
      const blur = i * 9;
      const alpha = (0.22 - i * 0.03).toFixed(2);
      layers.push((ox * d).toFixed(1) + "px " + (oy * d + i * 3).toFixed(1) + "px " + blur + "px rgba(23,20,26," + alpha + ")");
    }
    btn.style.boxShadow = layers.join(", ");
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(-0.4, 0.3);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      if (!hasPointerRef.current) {
        const s = syntheticTarget(t);
        targetXRef.current = s[0];
        targetYRef.current = s[1];
      }
      curXRef.current += (targetXRef.current - curXRef.current) * LERP;
      curYRef.current += (targetYRef.current - curYRef.current) * LERP;
      render(curXRef.current, curYRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function pointFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const nx = ((event.clientX - r.left) / r.width) * 2 - 1;
    const ny = ((event.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const p = pointFromEvent(event);
    targetXRef.current = p[0];
    targetYRef.current = p[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
    targetXRef.current = 0;
    targetYRef.current = 0;
  }

  function onClick(): void {
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = -0.8;
    targetYRef.current = 0.5;
    if (reduce) render(targetXRef.current, targetYRef.current);
    window.setTimeout(() => {
      if (!hasPointerRef.current) {
        targetXRef.current = 0;
        targetYRef.current = 0;
        if (reduce) render(targetXRef.current, targetYRef.current);
      }
    }, 240);
  }

  function onKeyDown(event: KeyEvt): void {
    const step = 0.22;
    const moves: { [key: string]: [number, number] } = {
      ArrowLeft: [-step, 0],
      ArrowRight: [step, 0],
      ArrowUp: [0, -step],
      ArrowDown: [0, step],
    };
    const m = moves[event.key];
    if (!m) return;
    event.preventDefault();
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = clamp(targetXRef.current + m[0], -1, 1);
    targetYRef.current = clamp(targetYRef.current + m[1], -1, 1);
    if (reduce) render(targetXRef.current, targetYRef.current);
  }

  const cls = [styles.sk, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>기운 방향의 반대쪽으로 그림자 세 겹이 어긋나 쌓입니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <button className={styles.btn} ref={btnRef} type="button" aria-label={LABEL} onClick={onClick} onKeyDown={onKeyDown}>
            <span className={styles.label}>지금 구매하기</span>
          </button>
        </div>
      </div>
    </main>
  );
}

<main class="stage">
<div class="ip is-demo" id="ip">
  <p class="ip__hint"><span>같은 좌표를 층마다 다른 배수로 곱해 아이콘이 글자보다 더 크게 움직입니다</span></p>
  <div class="ip__scene" id="scene">
    <button class="ip__btn" id="btn" type="button" aria-label="다운로드 — 아이콘이 앞층에서 시차로 움직이는 버튼">
      <span class="ip__icon" id="icon" aria-hidden="true">
        <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" width="22" height="22"><g fill="currentColor"><path d="M184 120v61.65a8 8 0 0 1-2.34 5.65l-34.35 34.35a8 8 0 0 1-13.57-4.53L128 176Zm-48-48H74.35a8 8 0 0 0-5.65 2.34l-34.35 34.35a8 8 0 0 0 4.53 13.57L80 128ZM40 216c37.65 0 50.69-19.69 54.56-28.18l-26.38-26.38C59.69 165.31 40 178.35 40 216" opacity=".35"/><path d="M223.85 47.12a16 16 0 0 0-15-15c-12.58-.75-44.73.4-71.41 27.07L132.69 64H74.36A15.9 15.9 0 0 0 63 68.68L28.7 103a16 16 0 0 0 9.07 27.16l38.47 5.37l44.21 44.21l5.37 38.49a15.94 15.94 0 0 0 10.78 12.92a16.1 16.1 0 0 0 5.1.83a15.9 15.9 0 0 0 11.3-4.68l34.32-34.3a15.9 15.9 0 0 0 4.68-11.36v-58.33l4.77-4.77c26.68-26.68 27.83-58.83 27.08-71.42M74.36 80h42.33l-39.53 39.52L40 114.34Zm74.41-9.45a76.65 76.65 0 0 1 59.11-22.47a76.46 76.46 0 0 1-22.42 59.16L128 164.68L91.32 128ZM176 181.64L141.67 216l-5.19-37.17L176 139.31Zm-74.16 9.5C97.34 201 82.29 224 40 224a8 8 0 0 1-8-8c0-42.29 23-57.34 32.86-61.85a8 8 0 0 1 6.64 14.56c-6.43 2.93-20.62 12.36-23.12 38.91c26.55-2.5 36-16.69 38.91-23.12a8 8 0 1 1 14.56 6.64Z"/></g></svg>
      </span>
      <span class="ip__label" id="label">다운로드</span>
    </button>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-paper);

.ip {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.ip__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba($subject-ink, .72);
}

.ip__scene {
  perspective: 640px;
  padding: $sp-6;
}

.ip__btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: $sp-2;
  border: 0;
  cursor: pointer;
  padding: $sp-4 $sp-8;
  border-radius: $r-control;
  background: $subject-ink;
  color: $subject-cream;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: $shadow-raised;
  overflow: hidden;
  will-change: transform;
}

.ip__btn:focus-visible {
  outline: 2px solid $subject-ink;
  outline-offset: 3px;
}

.ip__icon,
.ip__label {
  display: inline-flex;
  align-items: center;
  will-change: transform;
}

@media (prefers-reduced-motion: reduce) {
  .ip__btn { transition: none; }
}

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

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

.ip {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.ip__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba(23, 20, 26, 0.72);
}

.ip__scene {
  perspective: 640px;
  padding: 24px;
}

.ip__btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border: 0;
  cursor: pointer;
  padding: 16px 32px;
  border-radius: 12px;
  background: #17141a;
  color: #fff7e6;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  overflow: hidden;
  will-change: transform;
}

.ip__btn:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: 3px;
}

.ip__icon,
.ip__label {
  display: inline-flex;
  align-items: center;
  will-change: transform;
}

@media (prefers-reduced-motion: reduce) {
  .ip__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('ip');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var icon = document.getElementById('icon');
  var label = document.getElementById('label');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var LERP = 0.17;
  var ICON_DEPTH = 22;   // 아이콘 층 배수 — 앞에 떠 있어 더 크게 움직인다
  var LABEL_DEPTH = 8;   // 글자 층 배수 — 뒤에 있어 적게 움직인다
  var targetNX = 0, targetNY = 0;
  var curNX = 0, curNY = 0;
  var hasPointer = false;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }
  function syntheticTarget(t) { return [Math.sin(t * 1.05), Math.sin(t * 0.7 + 2.1)]; }

  function render(nx, ny) {
    btn.style.transform = 'rotateX(' + (-ny * 8).toFixed(2) + 'deg) rotateY(' + (nx * 8).toFixed(2) + 'deg)';
    icon.style.transform = 'translate3d(' + (nx * ICON_DEPTH).toFixed(1) + 'px, ' + (ny * ICON_DEPTH).toFixed(1) + 'px, 0)';
    label.style.transform = 'translate3d(' + (nx * LABEL_DEPTH).toFixed(1) + 'px, ' + (ny * LABEL_DEPTH).toFixed(1) + 'px, 0)';
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) t0 = now;
    var t = (now - t0) / 1000;
    if (!hasPointer && !reduce) {
      var s = syntheticTarget(t);
      targetNX = s[0]; targetNY = s[1];
    }
    curNX += (targetNX - curNX) * LERP;
    curNY += (targetNY - curNY) * LERP;
    render(curNX, curNY);
    requestAnimationFrame(loop);
  }

  function pointFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var nx = ((e.clientX - r.left) / r.width) * 2 - 1;
    var ny = ((e.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var p = pointFromEvent(e);
    targetNX = p[0]; targetNY = p[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
    targetNX = 0; targetNY = 0;
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNY = -1;
    if (reduce) { render(targetNX, targetNY); }
    setTimeout(function () { if (!hasPointer) { targetNX = 0; targetNY = 0; if (reduce) { render(targetNX, targetNY); } } }, 260);
  });
  btn.addEventListener('keydown', function (e) {
    var step = 0.24;
    var moves = { ArrowLeft: [-step, 0], ArrowRight: [step, 0], ArrowUp: [0, -step], ArrowDown: [0, step] };
    var m = moves[e.key];
    if (!m) return;
    e.preventDefault();
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = clamp(targetNX + m[0], -1, 1);
    targetNY = clamp(targetNY + m[1], -1, 1);
    if (reduce) { render(targetNX, targetNY); }
  });

  if (reduce) {
    render(0.3, -0.5);
  } else {
    requestAnimationFrame(loop);
  }
})();

// IconParallaxButton — vanilla 판(run/393/demo/04-pointer-tilt-3d-icon-parallax/index.html) 의 React 포트.
// 같은 정규화 좌표를 아이콘 층과 글자 층에 서로 다른 배수로 곱해 두 층이 다른 속도로 움직이는
// 시차(parallax) 를 만든다. 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./IconParallaxButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const ICON_DEPTH = 22;
const LABEL_DEPTH = 8;
const LERP = 0.17;
const LABEL = "다운로드 — 아이콘이 앞층에서 시차로 움직이는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}
function syntheticTarget(t: number): [number, number] {
  return [Math.sin(t * 1.05), Math.sin(t * 0.7 + 2.1)];
}

export default function IconParallaxButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const iconRef = useRef<HTMLSpanElement | null>(null);
  const labelRef = useRef<HTMLSpanElement | null>(null);
  const targetXRef = useRef<number>(0) as Box<number>;
  const targetYRef = useRef<number>(0) as Box<number>;
  const curXRef = useRef<number>(0) as Box<number>;
  const curYRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(nx: number, ny: number): void {
    const btn = btnRef.current;
    const icon = iconRef.current;
    const label = labelRef.current;
    if (!btn || !icon || !label) return;
    btn.style.transform = "rotateX(" + (-ny * 8).toFixed(2) + "deg) rotateY(" + (nx * 8).toFixed(2) + "deg)";
    icon.style.transform = "translate3d(" + (nx * ICON_DEPTH).toFixed(1) + "px, " + (ny * ICON_DEPTH).toFixed(1) + "px, 0)";
    label.style.transform = "translate3d(" + (nx * LABEL_DEPTH).toFixed(1) + "px, " + (ny * LABEL_DEPTH).toFixed(1) + "px, 0)";
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(0.3, -0.5);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      if (!hasPointerRef.current) {
        const s = syntheticTarget(t);
        targetXRef.current = s[0];
        targetYRef.current = s[1];
      }
      curXRef.current += (targetXRef.current - curXRef.current) * LERP;
      curYRef.current += (targetYRef.current - curYRef.current) * LERP;
      render(curXRef.current, curYRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function pointFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const nx = ((event.clientX - r.left) / r.width) * 2 - 1;
    const ny = ((event.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const p = pointFromEvent(event);
    targetXRef.current = p[0];
    targetYRef.current = p[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
    targetXRef.current = 0;
    targetYRef.current = 0;
  }

  function onClick(): void {
    setDemo(false);
    hasPointerRef.current = true;
    targetYRef.current = -1;
    if (reduce) render(targetXRef.current, targetYRef.current);
    window.setTimeout(() => {
      if (!hasPointerRef.current) {
        targetXRef.current = 0;
        targetYRef.current = 0;
        if (reduce) render(targetXRef.current, targetYRef.current);
      }
    }, 260);
  }

  function onKeyDown(event: KeyEvt): void {
    const step = 0.24;
    const moves: { [key: string]: [number, number] } = {
      ArrowLeft: [-step, 0],
      ArrowRight: [step, 0],
      ArrowUp: [0, -step],
      ArrowDown: [0, step],
    };
    const m = moves[event.key];
    if (!m) return;
    event.preventDefault();
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = clamp(targetXRef.current + m[0], -1, 1);
    targetYRef.current = clamp(targetYRef.current + m[1], -1, 1);
    if (reduce) render(targetXRef.current, targetYRef.current);
  }

  const cls = [styles.ip, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>같은 좌표를 층마다 다른 배수로 곱해 아이콘이 글자보다 더 크게 움직입니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <button className={styles.btn} ref={btnRef} type="button" aria-label={LABEL} onClick={onClick} onKeyDown={onKeyDown}>
            <span className={styles.icon} ref={iconRef} aria-hidden="true">
              <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" width="22" height="22">
                <g fill="currentColor">
                  <path
                    d="M184 120v61.65a8 8 0 0 1-2.34 5.65l-34.35 34.35a8 8 0 0 1-13.57-4.53L128 176Zm-48-48H74.35a8 8 0 0 0-5.65 2.34l-34.35 34.35a8 8 0 0 0 4.53 13.57L80 128ZM40 216c37.65 0 50.69-19.69 54.56-28.18l-26.38-26.38C59.69 165.31 40 178.35 40 216"
                    opacity=".35"
                  />
                  <path d="M223.85 47.12a16 16 0 0 0-15-15c-12.58-.75-44.73.4-71.41 27.07L132.69 64H74.36A15.9 15.9 0 0 0 63 68.68L28.7 103a16 16 0 0 0 9.07 27.16l38.47 5.37l44.21 44.21l5.37 38.49a15.94 15.94 0 0 0 10.78 12.92a16.1 16.1 0 0 0 5.1.83a15.9 15.9 0 0 0 11.3-4.68l34.32-34.3a15.9 15.9 0 0 0 4.68-11.36v-58.33l4.77-4.77c26.68-26.68 27.83-58.83 27.08-71.42M74.36 80h42.33l-39.53 39.52L40 114.34Zm74.41-9.45a76.65 76.65 0 0 1 59.11-22.47a76.46 76.46 0 0 1-22.42 59.16L128 164.68L91.32 128ZM176 181.64L141.67 216l-5.19-37.17L176 139.31Zm-74.16 9.5C97.34 201 82.29 224 40 224a8 8 0 0 1-8-8c0-42.29 23-57.34 32.86-61.85a8 8 0 0 1 6.64 14.56c-6.43 2.93-20.62 12.36-23.12 38.91c26.55-2.5 36-16.69 38.91-23.12a8 8 0 1 1 14.56 6.64Z" />
                </g>
              </svg>
            </span>
            <span className={styles.label} ref={labelRef}>
              다운로드
            </span>
          </button>
        </div>
      </div>
    </main>
  );
}

<main class="stage">
<div class="eb is-demo" id="eb">
  <p class="eb__hint"><span>기울기 크기를 각도로 바꿔 얇은 테두리 띠가 그 방향을 따라 밝아집니다</span></p>
  <div class="eb__scene" id="scene">
    <span class="eb__floor" id="floor" aria-hidden="true"></span>
    <div class="eb__wrap" id="wrap">
      <button class="eb__btn" id="btn" type="button" aria-label="자세히 보기 — 기울기 크기로 테두리가 밝아지는 버튼">
        <span class="eb__bevel" id="bevel" aria-hidden="true"></span>
        <span class="eb__label">자세히 보기</span>
      </button>
      <span class="eb__side" id="side" aria-hidden="true"></span>
    </div>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-ink);

.eb {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.eb__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba($subject-cream, .78);
}

.eb__scene {
  position: relative;
  perspective: 640px;
  padding: $sp-6;
}

// 바닥 그림자 — 기울기 방향으로 옮겨가며 면적을 만든다
.eb__floor {
  position: absolute;
  left: 50%;
  bottom: 4px;
  width: clamp(140px, 52vw, 250px);
  height: clamp(42px, 15.4vw, 74px);
  margin-left: clamp(-125px, -26vw, -70px);
  border-radius: 50%;
  background: radial-gradient(closest-side, rgba($subject-blue-light, .7), rgba($subject-blue-light, 0) 72%);
  filter: blur(10px);
  pointer-events: none;
}

.eb__wrap {
  position: relative;
  display: inline-block;
}

.eb__btn {
  position: relative;
  border: 1px solid rgba($subject-cream, .16);
  cursor: pointer;
  padding: $sp-6 $sp-12;
  border-radius: $r-control;
  background: rgba(255, 247, 230, .06);
  color: $subject-cream;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: $shadow-raised;
  overflow: hidden;
  will-change: transform;
}

.eb__btn:focus-visible {
  outline: 2px solid $subject-cream;
  outline-offset: 3px;
}

.eb__bevel {
  position: absolute;
  inset: -2px;
  border-radius: inherit;
  padding: 4px;
  pointer-events: none;
  mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  mask-composite: exclude;
  -webkit-mask-composite: xor;
}

// 측면 두께 — 버튼 아래 얇은 띠가 기운 크기만큼 길어져 옆면(두께)처럼 읽힌다
.eb__side {
  position: absolute;
  left: 8%;
  right: 8%;
  bottom: -4px;
  height: 10px;
  border-radius: 0 0 $r-control $r-control;
  background: linear-gradient(180deg, rgba($subject-blue-light, .6), rgba($subject-blue-deep, 0));
  transform-origin: top center;
  pointer-events: none;
}

.eb__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .eb__btn { transition: none; }
}

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);
}

.eb {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.eb__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba(255, 247, 230, 0.78);
}

.eb__scene {
  position: relative;
  perspective: 640px;
  padding: 24px;
}

.eb__floor {
  position: absolute;
  left: 50%;
  bottom: 4px;
  width: clamp(140px, 52vw, 250px);
  height: clamp(42px, 15.4vw, 74px);
  margin-left: clamp(-125px, -26vw, -70px);
  border-radius: 50%;
  background: radial-gradient(closest-side, rgba(91, 140, 248, 0.7), rgba(91, 140, 248, 0) 72%);
  filter: blur(10px);
  pointer-events: none;
}

.eb__wrap {
  position: relative;
  display: inline-block;
}

.eb__btn {
  position: relative;
  border: 1px solid rgba(255, 247, 230, 0.16);
  cursor: pointer;
  padding: 24px 48px;
  border-radius: 12px;
  background: rgba(255, 247, 230, 0.06);
  color: #fff7e6;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  overflow: hidden;
  will-change: transform;
}

.eb__btn:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 3px;
}

.eb__bevel {
  position: absolute;
  inset: -2px;
  border-radius: inherit;
  padding: 4px;
  pointer-events: none;
  mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  mask-composite: exclude;
  -webkit-mask-composite: xor;
}

.eb__side {
  position: absolute;
  left: 8%;
  right: 8%;
  bottom: -4px;
  height: 10px;
  border-radius: 0 0 12px 12px;
  background: linear-gradient(180deg, rgba(91, 140, 248, 0.6), rgba(10, 79, 232, 0));
  transform-origin: top center;
  pointer-events: none;
}

.eb__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .eb__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('eb');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var bevel = document.getElementById('bevel');
  var floor = document.getElementById('floor');
  var side = document.getElementById('side');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var MAX_DEG = 13;   // 불변
  var LERP = 0.16;
  var targetNX = 0, targetNY = 0;
  var curNX = 0, curNY = 0;
  var hasPointer = false;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }
  function syntheticTarget(t) { return [Math.sin(t * 1.2 + 0.6), Math.sin(t * 0.88)]; }

  // 기울기 벡터의 각도·크기 → conic-gradient 회전각·광 폭. 테두리 광의 위치는 기운 방향과 같다
  // 폭·대비를 키워 테두리 띠가 버튼 변 전체를 가로지르게 한다 — MAX_DEG(기울기 각) 값은 그대로
  function render(nx, ny) {
    var rotY = nx * MAX_DEG;
    var rotX = -ny * MAX_DEG;
    btn.style.transform = 'rotateX(' + rotX.toFixed(2) + 'deg) rotateY(' + rotY.toFixed(2) + 'deg)';
    var mag = clamp(Math.sqrt(nx * nx + ny * ny), 0, 1);
    var ang = Math.atan2(ny, nx) * 180 / Math.PI + 90;
    var width = 70 + mag * 110;
    var alpha = (0.38 + mag * 0.6).toFixed(2);
    bevel.style.background = 'conic-gradient(from ' + ang.toFixed(1) + 'deg, rgba(91,140,248,0), rgba(91,140,248,' + alpha + ') ' + (width / 2).toFixed(1) + 'deg, rgba(91,140,248,0) ' + width.toFixed(1) + 'deg)';
    // 바닥 그림자 — 기운 방향으로 옮겨간다
    var floorShift = nx * 46;
    floor.style.transform = 'translateX(' + floorShift.toFixed(1) + 'px) scale(' + (1 + mag * 0.4).toFixed(2) + ')';
    floor.style.opacity = (0.14 + mag * 0.7).toFixed(2);
    // 측면 두께 — 기운 크기만큼 버튼 아래 「옆면」이 길어져 3D 두께로 읽힌다(MAX_DEG 불변, 순수 표현 한 겹)
    side.style.transform = 'scaleY(' + (0.4 + mag * 2.6).toFixed(2) + ')';
    side.style.opacity = (0.25 + mag * 0.7).toFixed(2);
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) t0 = now;
    var t = (now - t0) / 1000;
    if (!hasPointer && !reduce) {
      var s = syntheticTarget(t);
      targetNX = s[0]; targetNY = s[1];
    }
    curNX += (targetNX - curNX) * LERP;
    curNY += (targetNY - curNY) * LERP;
    render(curNX, curNY);
    requestAnimationFrame(loop);
  }

  function pointFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var nx = ((e.clientX - r.left) / r.width) * 2 - 1;
    var ny = ((e.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var p = pointFromEvent(e);
    targetNX = p[0]; targetNY = p[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
    targetNX = 0; targetNY = 0;
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = 0.9; targetNY = 0.9;
    if (reduce) { render(targetNX, targetNY); }
    setTimeout(function () { if (!hasPointer) { targetNX = 0; targetNY = 0; if (reduce) { render(targetNX, targetNY); } } }, 240);
  });
  btn.addEventListener('keydown', function (e) {
    var step = 0.24;
    var moves = { ArrowLeft: [-step, 0], ArrowRight: [step, 0], ArrowUp: [0, -step], ArrowDown: [0, step] };
    var m = moves[e.key];
    if (!m) return;
    e.preventDefault();
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = clamp(targetNX + m[0], -1, 1);
    targetNY = clamp(targetNY + m[1], -1, 1);
    if (reduce) { render(targetNX, targetNY); }
  });

  if (reduce) {
    render(0.5, 0.5);
  } else {
    requestAnimationFrame(loop);
  }
})();

// EdgeBevelButton — vanilla 판(run/393/demo/05-pointer-tilt-3d-edge-bevel/index.html) 의 React 포트.
// 기울기 벡터의 각도(atan2)·크기를 conic-gradient 의 회전각·광 폭·투명도로 바꿔 테두리 띠가
// 기운 방향을 따라 밝아지게 한다. 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./EdgeBevelButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const MAX_DEG = 13; // 불변
const LERP = 0.16;
const LABEL = "자세히 보기 — 기울기 크기로 테두리가 밝아지는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}
function syntheticTarget(t: number): [number, number] {
  return [Math.sin(t * 1.2 + 0.6), Math.sin(t * 0.88)];
}

export default function EdgeBevelButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const bevelRef = useRef<HTMLSpanElement | null>(null);
  const floorRef = useRef<HTMLSpanElement | null>(null);
  const sideRef = useRef<HTMLSpanElement | null>(null);
  const targetXRef = useRef<number>(0) as Box<number>;
  const targetYRef = useRef<number>(0) as Box<number>;
  const curXRef = useRef<number>(0) as Box<number>;
  const curYRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(nx: number, ny: number): void {
    const btn = btnRef.current;
    const bevel = bevelRef.current;
    const floor = floorRef.current;
    const side = sideRef.current;
    if (!btn || !bevel || !floor || !side) return;
    const rotY = nx * MAX_DEG;
    const rotX = -ny * MAX_DEG;
    btn.style.transform = "rotateX(" + rotX.toFixed(2) + "deg) rotateY(" + rotY.toFixed(2) + "deg)";
    const mag = clamp(Math.sqrt(nx * nx + ny * ny), 0, 1);
    const ang = (Math.atan2(ny, nx) * 180) / Math.PI + 90;
    const width = 70 + mag * 110;
    const alpha = (0.38 + mag * 0.6).toFixed(2);
    bevel.style.background =
      "conic-gradient(from " + ang.toFixed(1) + "deg, rgba(91,140,248,0), rgba(91,140,248," + alpha + ") " + (width / 2).toFixed(1) + "deg, rgba(91,140,248,0) " + width.toFixed(1) + "deg)";
    const floorShift = nx * 46;
    floor.style.transform = "translateX(" + floorShift.toFixed(1) + "px) scale(" + (1 + mag * 0.4).toFixed(2) + ")";
    floor.style.opacity = (0.14 + mag * 0.7).toFixed(2);
    side.style.transform = "scaleY(" + (0.4 + mag * 2.6).toFixed(2) + ")";
    side.style.opacity = (0.25 + mag * 0.7).toFixed(2);
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(0.5, 0.5);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      if (!hasPointerRef.current) {
        const s = syntheticTarget(t);
        targetXRef.current = s[0];
        targetYRef.current = s[1];
      }
      curXRef.current += (targetXRef.current - curXRef.current) * LERP;
      curYRef.current += (targetYRef.current - curYRef.current) * LERP;
      render(curXRef.current, curYRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function pointFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const nx = ((event.clientX - r.left) / r.width) * 2 - 1;
    const ny = ((event.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const p = pointFromEvent(event);
    targetXRef.current = p[0];
    targetYRef.current = p[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
    targetXRef.current = 0;
    targetYRef.current = 0;
  }

  function onClick(): void {
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = 0.9;
    targetYRef.current = 0.9;
    if (reduce) render(targetXRef.current, targetYRef.current);
    window.setTimeout(() => {
      if (!hasPointerRef.current) {
        targetXRef.current = 0;
        targetYRef.current = 0;
        if (reduce) render(targetXRef.current, targetYRef.current);
      }
    }, 240);
  }

  function onKeyDown(event: KeyEvt): void {
    const step = 0.24;
    const moves: { [key: string]: [number, number] } = {
      ArrowLeft: [-step, 0],
      ArrowRight: [step, 0],
      ArrowUp: [0, -step],
      ArrowDown: [0, step],
    };
    const m = moves[event.key];
    if (!m) return;
    event.preventDefault();
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = clamp(targetXRef.current + m[0], -1, 1);
    targetYRef.current = clamp(targetYRef.current + m[1], -1, 1);
    if (reduce) render(targetXRef.current, targetYRef.current);
  }

  const cls = [styles.eb, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>기울기 크기를 각도로 바꿔 얇은 테두리 띠가 그 방향을 따라 밝아집니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <span className={styles.floor} ref={floorRef} aria-hidden="true" />
          <div className={styles.wrap}>
            <button className={styles.btn} ref={btnRef} type="button" aria-label={LABEL} onClick={onClick} onKeyDown={onKeyDown}>
              <span className={styles.bevel} ref={bevelRef} aria-hidden="true" />
              <span className={styles.label}>자세히 보기</span>
            </button>
            <span className={styles.side} ref={sideRef} aria-hidden="true" />
          </div>
        </div>
      </div>
    </main>
  );
}

<main class="stage">
<div class="pj is-demo" id="pj">
  <p class="pj__hint"><span>누르고 있던 시간이 눌림 깊이가 되어, 놓으면 그 깊이만큼 스프링 감쇠가 달라집니다</span></p>
  <div class="pj__scene" id="scene">
    <button class="pj__btn" id="btn" type="button" aria-label="제출하기 — 누른 깊이만큼 스프링으로 튕겨 돌아오는 버튼">
      <span class="pj__label">제출하기</span>
    </button>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-yellow);

.pj {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.pj__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba($subject-ink, .78);
}

.pj__scene {
  perspective: 640px;
  padding: $sp-6;
}

.pj__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: $sp-4 $sp-10;
  border-radius: $r-control;
  background: $subject-ink;
  color: $subject-cream;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  will-change: transform;
}

.pj__btn:focus-visible {
  outline: 2px solid $subject-ink;
  outline-offset: 3px;
}

.pj__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .pj__btn { transition: none; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.pj {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.pj__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba(23, 20, 26, 0.78);
}

.pj__scene {
  perspective: 640px;
  padding: 24px;
}

.pj__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: 16px 40px;
  border-radius: 12px;
  background: #17141a;
  color: #fff7e6;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  will-change: transform;
}

.pj__btn:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: 3px;
}

.pj__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .pj__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('pj');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var PERIOD = 2.4;              // 합성 시연 한 주기(초)
  var STIFFNESS = 0.28;
  var DAMP_BASE = 0.60;          // 감쇠 하한 — 얕게 누르면 빨리 정착
  var DAMP_DEPTH_RANGE = 0.32;   // 눌림 깊이가 더할수록 감쇠가 늘어 더 크게 튄다
  var PRESS_DEPTH_CAP = 480;     // 이 시간(ms) 이상 누르면 깊이 1
  var MAX_DEG = 6;
  var LERP = 0.16;

  var targetNX = 0, targetNY = 0, curNX = 0, curNY = 0;
  var hasPointer = false;
  var pressedReal = false;
  var wasHeld = false;
  var pressStartNow = 0;
  var damping = DAMP_BASE;
  var aimZ = 0, curZ = 0, velZ = 0;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }
  function syntheticTarget(t) { return [Math.sin(t * 0.7 + 1.1), Math.sin(t * 0.5)]; }

  // 눌리는 지속시간이 다른 합성 사이클을 반복해 눌림 깊이 차이를 보여준다(고정 시드)
  function syntheticHold(t) {
    var cycle = Math.floor(t / PERIOD);
    var phase = t - cycle * PERIOD;
    var holdFrac = 0.14 + 0.18 * (0.5 + 0.5 * Math.sin(cycle * 1.7));
    return phase < PERIOD * holdFrac;
  }

  function render(nx, ny, z) {
    var rotY = nx * MAX_DEG;
    var rotX = -ny * MAX_DEG;
    btn.style.transform = 'rotateX(' + rotX.toFixed(2) + 'deg) rotateY(' + rotY.toFixed(2) + 'deg) translateZ(' + z.toFixed(2) + 'px)';
    var shadowScale = clamp(1 + z / 60, 0.35, 1.25);
    btn.style.boxShadow = '0 ' + (14 * shadowScale).toFixed(1) + 'px ' + (24 * shadowScale).toFixed(1) + 'px rgba(23,20,26,.30)';
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) t0 = now;
    var t = (now - t0) / 1000;
    var heldSynthetic = false;
    if (!hasPointer && !reduce) {
      var s = syntheticTarget(t);
      targetNX = s[0]; targetNY = s[1];
      heldSynthetic = syntheticHold(t);
    }
    var held = pressedReal || heldSynthetic;
    if (held && !wasHeld) { pressStartNow = now; }
    if (!held && wasHeld) {
      var heldMs = now - pressStartNow;
      var depth = clamp(heldMs / PRESS_DEPTH_CAP, 0, 1);
      damping = DAMP_BASE + depth * DAMP_DEPTH_RANGE;
    }
    wasHeld = held;
    aimZ = held ? -14 : 0;

    curNX += (targetNX - curNX) * LERP;
    curNY += (targetNY - curNY) * LERP;
    velZ = (velZ + (aimZ - curZ) * STIFFNESS) * damping;
    curZ += velZ;
    render(curNX, curNY, curZ);
    requestAnimationFrame(loop);
  }

  function pointFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var nx = ((e.clientX - r.left) / r.width) * 2 - 1;
    var ny = ((e.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var p = pointFromEvent(e);
    targetNX = p[0]; targetNY = p[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
    targetNX = 0; targetNY = 0;
    pressedReal = false;
  });
  btn.addEventListener('pointerdown', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    pressedReal = true;
    if (reduce) { render(targetNX, targetNY, -14); }
  });
  btn.addEventListener('pointerup', function () {
    pressedReal = false;
    if (reduce) { render(targetNX, targetNY, 0); }
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
  });
  btn.addEventListener('keydown', function (e) {
    if (e.key === ' ' || e.key === 'Enter') {
      root.classList.remove('is-demo');
      hasPointer = true;
      pressedReal = true;
      if (reduce) { render(targetNX, targetNY, -14); }
    }
  });
  btn.addEventListener('keyup', function (e) {
    if (e.key === ' ' || e.key === 'Enter') {
      pressedReal = false;
      if (reduce) { render(targetNX, targetNY, 0); }
    }
  });

  if (reduce) {
    render(0.3, 0.2, -14);
  } else {
    requestAnimationFrame(loop);
  }
})();

// PressSpringButton — vanilla 판(run/393/demo/06-pointer-tilt-3d-press-release-spring/index.html) 의 React 포트.
// 누르고 있던 시간을 눌림 깊이(0~1)로 바꾸고, 놓는 순간 그 깊이로 스프링 감쇠(damping)를 정해
// velocity·damping 한 식으로 관성과 오버슛을 만든다. 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./PressSpringButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const PERIOD = 2.4;
const STIFFNESS = 0.28;
const DAMP_BASE = 0.6;
const DAMP_DEPTH_RANGE = 0.32;
const PRESS_DEPTH_CAP = 480;
const MAX_DEG = 6;
const LERP = 0.16;
const LABEL = "제출하기 — 누른 깊이만큼 스프링으로 튕겨 돌아오는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}
function syntheticTarget(t: number): [number, number] {
  return [Math.sin(t * 0.7 + 1.1), Math.sin(t * 0.5)];
}
function syntheticHold(t: number): boolean {
  const cycle = Math.floor(t / PERIOD);
  const phase = t - cycle * PERIOD;
  const holdFrac = 0.14 + 0.18 * (0.5 + 0.5 * Math.sin(cycle * 1.7));
  return phase < PERIOD * holdFrac;
}

export default function PressSpringButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const targetXRef = useRef<number>(0) as Box<number>;
  const targetYRef = useRef<number>(0) as Box<number>;
  const curXRef = useRef<number>(0) as Box<number>;
  const curYRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const pressedRealRef = useRef<boolean>(false) as Box<boolean>;
  const wasHeldRef = useRef<boolean>(false) as Box<boolean>;
  const pressStartRef = useRef<number>(0) as Box<number>;
  const dampingRef = useRef<number>(DAMP_BASE) as Box<number>;
  const aimZRef = useRef<number>(0) as Box<number>;
  const curZRef = useRef<number>(0) as Box<number>;
  const velZRef = useRef<number>(0) as Box<number>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(nx: number, ny: number, z: number): void {
    const btn = btnRef.current;
    if (!btn) return;
    const rotY = nx * MAX_DEG;
    const rotX = -ny * MAX_DEG;
    btn.style.transform = "rotateX(" + rotX.toFixed(2) + "deg) rotateY(" + rotY.toFixed(2) + "deg) translateZ(" + z.toFixed(2) + "px)";
    const shadowScale = clamp(1 + z / 60, 0.35, 1.25);
    btn.style.boxShadow = "0 " + (14 * shadowScale).toFixed(1) + "px " + (24 * shadowScale).toFixed(1) + "px rgba(23,20,26,.30)";
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(0.3, 0.2, -14);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      let heldSynthetic = false;
      if (!hasPointerRef.current) {
        const s = syntheticTarget(t);
        targetXRef.current = s[0];
        targetYRef.current = s[1];
        heldSynthetic = syntheticHold(t);
      }
      const held = pressedRealRef.current || heldSynthetic;
      if (held && !wasHeldRef.current) {
        pressStartRef.current = now;
      }
      if (!held && wasHeldRef.current) {
        const heldMs = now - pressStartRef.current;
        const depth = clamp(heldMs / PRESS_DEPTH_CAP, 0, 1);
        dampingRef.current = DAMP_BASE + depth * DAMP_DEPTH_RANGE;
      }
      wasHeldRef.current = held;
      aimZRef.current = held ? -14 : 0;

      curXRef.current += (targetXRef.current - curXRef.current) * LERP;
      curYRef.current += (targetYRef.current - curYRef.current) * LERP;
      velZRef.current = (velZRef.current + (aimZRef.current - curZRef.current) * STIFFNESS) * dampingRef.current;
      curZRef.current += velZRef.current;
      render(curXRef.current, curYRef.current, curZRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function pointFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const nx = ((event.clientX - r.left) / r.width) * 2 - 1;
    const ny = ((event.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const p = pointFromEvent(event);
    targetXRef.current = p[0];
    targetYRef.current = p[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
    targetXRef.current = 0;
    targetYRef.current = 0;
    pressedRealRef.current = false;
  }

  function onPointerDown(): void {
    setDemo(false);
    hasPointerRef.current = true;
    pressedRealRef.current = true;
    if (reduce) render(targetXRef.current, targetYRef.current, -14);
  }

  function onPointerUp(): void {
    pressedRealRef.current = false;
    if (reduce) render(targetXRef.current, targetYRef.current, 0);
  }

  function onKeyDown(event: KeyEvt): void {
    if (event.key === " " || event.key === "Enter") {
      setDemo(false);
      hasPointerRef.current = true;
      pressedRealRef.current = true;
      if (reduce) render(targetXRef.current, targetYRef.current, -14);
    }
  }

  function onKeyUp(event: KeyEvt): void {
    if (event.key === " " || event.key === "Enter") {
      pressedRealRef.current = false;
      if (reduce) render(targetXRef.current, targetYRef.current, 0);
    }
  }

  const cls = [styles.pj, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>누르고 있던 시간이 눌림 깊이가 되어, 놓으면 그 깊이만큼 스프링 감쇠가 달라집니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <button
            className={styles.btn}
            ref={btnRef}
            type="button"
            aria-label={LABEL}
            onPointerDown={onPointerDown}
            onPointerUp={onPointerUp}
            onKeyDown={onKeyDown}
            onKeyUp={onKeyUp}
          >
            <span className={styles.label}>제출하기</span>
          </button>
        </div>
      </div>
    </main>
  );
}

<main class="stage">
<div class="gp is-demo" id="gp">
  <p class="gp__hint"><span>같은 좌표를 배수 둘로 곱해 안쪽 격자와 바깥 격자가 서로 다른 속도로 어긋납니다</span></p>
  <div class="gp__scene" id="scene">
    <button class="gp__btn" id="btn" type="button" aria-label="컬렉션 보기 — 격자 두 겹이 시차로 어긋나는 버튼">
      <span class="gp__grid gp__grid--far" id="gridFar" aria-hidden="true"></span>
      <span class="gp__grid gp__grid--near" id="gridNear" aria-hidden="true"></span>
      <span class="gp__label">컬렉션 보기</span>
    </button>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-orange);

.gp {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.gp__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: $subject-ink;
}

.gp__scene {
  perspective: 640px;
  padding: $sp-6;
}

.gp__btn {
  position: relative;
  border: 1px solid rgba($subject-ink, .14);
  cursor: pointer;
  padding: $sp-4 $sp-8;
  border-radius: $r-control;
  background: rgba(255, 247, 230, .82);
  color: $subject-ink;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: $shadow-raised;
  overflow: hidden;
  will-change: transform;
}

.gp__btn:focus-visible {
  outline: 2px solid $subject-ink;
  outline-offset: 3px;
}

.gp__grid {
  position: absolute;
  inset: -30%;
  pointer-events: none;
  background-repeat: repeat;
  background-size: 18px 18px;
}

.gp__grid--far {
  background-image: radial-gradient(rgba(23, 20, 26, .1) 1px, transparent 1px);
  opacity: .5;
}

.gp__grid--near {
  background-image: radial-gradient(rgba(23, 20, 26, .18) 1.4px, transparent 1.4px);
  background-size: 12px 12px;
}

.gp__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .gp__btn { transition: none; }
}

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);
}

.gp {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.gp__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: #17141a;
}

.gp__scene {
  perspective: 640px;
  padding: 24px;
}

.gp__btn {
  position: relative;
  border: 1px solid rgba(23, 20, 26, 0.14);
  cursor: pointer;
  padding: 16px 32px;
  border-radius: 12px;
  background: rgba(255, 247, 230, 0.82);
  color: #17141a;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  overflow: hidden;
  will-change: transform;
}

.gp__btn:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: 3px;
}

.gp__grid {
  position: absolute;
  inset: -30%;
  pointer-events: none;
  background-repeat: repeat;
  background-size: 18px 18px;
}

.gp__grid--far {
  background-image: radial-gradient(rgba(23, 20, 26, 0.1) 1px, transparent 1px);
  opacity: 0.5;
}

.gp__grid--near {
  background-image: radial-gradient(rgba(23, 20, 26, 0.18) 1.4px, transparent 1.4px);
  background-size: 12px 12px;
}

.gp__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .gp__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('gp');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var gridFar = document.getElementById('gridFar');
  var gridNear = document.getElementById('gridNear');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var MAX_DEG = 9;
  var LERP = 0.16;
  var FAR_DEPTH = 10;
  var NEAR_DEPTH = 26;
  var targetNX = 0, targetNY = 0, curNX = 0, curNY = 0;
  var hasPointer = false;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }
  function syntheticTarget(t) { return [Math.sin(t * 0.9), Math.sin(t * 1.4 + 1.6)]; }

  function render(nx, ny) {
    btn.style.transform = 'rotateX(' + (-ny * MAX_DEG).toFixed(2) + 'deg) rotateY(' + (nx * MAX_DEG).toFixed(2) + 'deg)';
    gridFar.style.backgroundPosition = (nx * FAR_DEPTH).toFixed(1) + 'px ' + (ny * FAR_DEPTH).toFixed(1) + 'px';
    gridNear.style.backgroundPosition = (-nx * NEAR_DEPTH).toFixed(1) + 'px ' + (-ny * NEAR_DEPTH).toFixed(1) + 'px';
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) t0 = now;
    var t = (now - t0) / 1000;
    if (!hasPointer && !reduce) {
      var s = syntheticTarget(t);
      targetNX = s[0]; targetNY = s[1];
    }
    curNX += (targetNX - curNX) * LERP;
    curNY += (targetNY - curNY) * LERP;
    render(curNX, curNY);
    requestAnimationFrame(loop);
  }

  function pointFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var nx = ((e.clientX - r.left) / r.width) * 2 - 1;
    var ny = ((e.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var p = pointFromEvent(e);
    targetNX = p[0]; targetNY = p[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
    targetNX = 0; targetNY = 0;
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = -0.85; targetNY = -0.4;
    if (reduce) { render(targetNX, targetNY); }
    setTimeout(function () { if (!hasPointer) { targetNX = 0; targetNY = 0; if (reduce) { render(targetNX, targetNY); } } }, 240);
  });
  btn.addEventListener('keydown', function (e) {
    var step = 0.24;
    var moves = { ArrowLeft: [-step, 0], ArrowRight: [step, 0], ArrowUp: [0, -step], ArrowDown: [0, step] };
    var m = moves[e.key];
    if (!m) return;
    e.preventDefault();
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = clamp(targetNX + m[0], -1, 1);
    targetNY = clamp(targetNY + m[1], -1, 1);
    if (reduce) { render(targetNX, targetNY); }
  });

  if (reduce) {
    render(0.4, -0.3);
  } else {
    requestAnimationFrame(loop);
  }
})();

// GridParallaxButton — vanilla 판(run/393/demo/07-pointer-tilt-3d-grid-parallax/index.html) 의 React 포트.
// 같은 정규화 좌표를 두 격자 층에 서로 다른 배수·부호로 곱해 배경 위치를 옮긴다 — 두 층이
// 다른 속도로 어긋나며 시차(parallax) 깊이를 만든다. 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./GridParallaxButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const MAX_DEG = 9;
const LERP = 0.16;
const FAR_DEPTH = 10;
const NEAR_DEPTH = 26;
const LABEL = "컬렉션 보기 — 격자 두 겹이 시차로 어긋나는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}
function syntheticTarget(t: number): [number, number] {
  return [Math.sin(t * 0.9), Math.sin(t * 1.4 + 1.6)];
}

export default function GridParallaxButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const gridFarRef = useRef<HTMLSpanElement | null>(null);
  const gridNearRef = useRef<HTMLSpanElement | null>(null);
  const targetXRef = useRef<number>(0) as Box<number>;
  const targetYRef = useRef<number>(0) as Box<number>;
  const curXRef = useRef<number>(0) as Box<number>;
  const curYRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(nx: number, ny: number): void {
    const btn = btnRef.current;
    const gridFar = gridFarRef.current;
    const gridNear = gridNearRef.current;
    if (!btn || !gridFar || !gridNear) return;
    btn.style.transform = "rotateX(" + (-ny * MAX_DEG).toFixed(2) + "deg) rotateY(" + (nx * MAX_DEG).toFixed(2) + "deg)";
    gridFar.style.backgroundPosition = (nx * FAR_DEPTH).toFixed(1) + "px " + (ny * FAR_DEPTH).toFixed(1) + "px";
    gridNear.style.backgroundPosition = (-nx * NEAR_DEPTH).toFixed(1) + "px " + (-ny * NEAR_DEPTH).toFixed(1) + "px";
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(0.4, -0.3);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      if (!hasPointerRef.current) {
        const s = syntheticTarget(t);
        targetXRef.current = s[0];
        targetYRef.current = s[1];
      }
      curXRef.current += (targetXRef.current - curXRef.current) * LERP;
      curYRef.current += (targetYRef.current - curYRef.current) * LERP;
      render(curXRef.current, curYRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function pointFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const nx = ((event.clientX - r.left) / r.width) * 2 - 1;
    const ny = ((event.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const p = pointFromEvent(event);
    targetXRef.current = p[0];
    targetYRef.current = p[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
    targetXRef.current = 0;
    targetYRef.current = 0;
  }

  function onClick(): void {
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = -0.85;
    targetYRef.current = -0.4;
    if (reduce) render(targetXRef.current, targetYRef.current);
    window.setTimeout(() => {
      if (!hasPointerRef.current) {
        targetXRef.current = 0;
        targetYRef.current = 0;
        if (reduce) render(targetXRef.current, targetYRef.current);
      }
    }, 240);
  }

  function onKeyDown(event: KeyEvt): void {
    const step = 0.24;
    const moves: { [key: string]: [number, number] } = {
      ArrowLeft: [-step, 0],
      ArrowRight: [step, 0],
      ArrowUp: [0, -step],
      ArrowDown: [0, step],
    };
    const m = moves[event.key];
    if (!m) return;
    event.preventDefault();
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = clamp(targetXRef.current + m[0], -1, 1);
    targetYRef.current = clamp(targetYRef.current + m[1], -1, 1);
    if (reduce) render(targetXRef.current, targetYRef.current);
  }

  const cls = [styles.gp, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>같은 좌표를 배수 둘로 곱해 안쪽 격자와 바깥 격자가 서로 다른 속도로 어긋납니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <button className={styles.btn} ref={btnRef} type="button" aria-label={LABEL} onClick={onClick} onKeyDown={onKeyDown}>
            <span className={`${styles.grid} ${styles.gridFar}`} ref={gridFarRef} aria-hidden="true" />
            <span className={`${styles.grid} ${styles.gridNear}`} ref={gridNearRef} aria-hidden="true" />
            <span className={styles.label}>컬렉션 보기</span>
          </button>
        </div>
      </div>
    </main>
  );
}

<main class="stage">
<div class="rg is-demo" id="rg">
  <p class="rg__hint"><span>기울기 크기(방향과 무관)만 골라 둘레 전체의 광 반경·밝기로 바꿉니다</span></p>
  <div class="rg__scene" id="scene">
    <button class="rg__btn" id="btn" type="button" aria-label="지금 플레이 — 기울기 크기로 둘레가 밝아지는 버튼">
      <span class="rg__label">지금 플레이</span>
    </button>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-paper);

.rg {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.rg__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba($subject-ink, .72);
}

.rg__scene {
  perspective: 640px;
  padding: $sp-6;
}

.rg__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: $sp-4 $sp-8;
  border-radius: $r-control;
  background: $subject-ink;
  color: $subject-cream;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  will-change: transform, box-shadow;
}

.rg__btn:focus-visible {
  outline: 2px solid $subject-blue-light;
  outline-offset: 3px;
}

.rg__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .rg__btn { transition: none; }
}

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

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

.rg {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.rg__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba(23, 20, 26, 0.72);
}

.rg__scene {
  perspective: 640px;
  padding: 24px;
}

.rg__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: 16px 32px;
  border-radius: 12px;
  background: #17141a;
  color: #fff7e6;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  will-change: transform, box-shadow;
}

.rg__btn:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 3px;
}

.rg__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .rg__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('rg');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var MAX_DEG = 10;
  var LERP = 0.16;
  var BLUR_BASE = 6;
  var BLUR_RANGE = 34;
  var targetNX = 0, targetNY = 0, curNX = 0, curNY = 0;
  var hasPointer = false;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }
  function syntheticTarget(t) { return [Math.sin(t * 1.1 + 0.3), Math.sin(t * 1.6)]; }

  // 방향은 회전에만 쓰고, 둘레 광은 크기(magnitude)만 읽는다 — 05 의 방향성 광과 다른 값이다
  function render(nx, ny) {
    btn.style.transform = 'rotateX(' + (-ny * MAX_DEG).toFixed(2) + 'deg) rotateY(' + (nx * MAX_DEG).toFixed(2) + 'deg)';
    var mag = clamp(Math.sqrt(nx * nx + ny * ny), 0, 1);
    var blur = BLUR_BASE + mag * BLUR_RANGE;
    var spread = 1 + mag * 5;
    var alpha = (0.28 + mag * 0.5).toFixed(2);
    btn.style.boxShadow = '0 0 ' + blur.toFixed(1) + 'px ' + spread.toFixed(1) + 'px rgba(91,140,248,' + alpha + '), 0 12px 20px rgba(23,20,26,.28)';
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) t0 = now;
    var t = (now - t0) / 1000;
    if (!hasPointer && !reduce) {
      var s = syntheticTarget(t);
      targetNX = s[0]; targetNY = s[1];
    }
    curNX += (targetNX - curNX) * LERP;
    curNY += (targetNY - curNY) * LERP;
    render(curNX, curNY);
    requestAnimationFrame(loop);
  }

  function pointFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var nx = ((e.clientX - r.left) / r.width) * 2 - 1;
    var ny = ((e.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var p = pointFromEvent(e);
    targetNX = p[0]; targetNY = p[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
    targetNX = 0; targetNY = 0;
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = 0.95; targetNY = 0.3;
    if (reduce) { render(targetNX, targetNY); }
    setTimeout(function () { if (!hasPointer) { targetNX = 0; targetNY = 0; if (reduce) { render(targetNX, targetNY); } } }, 240);
  });
  btn.addEventListener('keydown', function (e) {
    var step = 0.24;
    var moves = { ArrowLeft: [-step, 0], ArrowRight: [step, 0], ArrowUp: [0, -step], ArrowDown: [0, step] };
    var m = moves[e.key];
    if (!m) return;
    e.preventDefault();
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = clamp(targetNX + m[0], -1, 1);
    targetNY = clamp(targetNY + m[1], -1, 1);
    if (reduce) { render(targetNX, targetNY); }
  });

  if (reduce) {
    render(0.5, 0.4);
  } else {
    requestAnimationFrame(loop);
  }
})();

// RimGlowButton — vanilla 판(run/393/demo/08-pointer-tilt-3d-rim-glow/index.html) 의 React 포트.
// 기울기 벡터에서 방향은 회전에만 쓰고, 크기(magnitude)만 따로 읽어 둘레 광의 반경·번짐·밝기로
// 바꾼다(05 의 방향성 테두리 광과는 다른 값). 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./RimGlowButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const MAX_DEG = 10;
const LERP = 0.16;
const BLUR_BASE = 6;
const BLUR_RANGE = 34;
const LABEL = "지금 플레이 — 기울기 크기로 둘레가 밝아지는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}
function syntheticTarget(t: number): [number, number] {
  return [Math.sin(t * 1.1 + 0.3), Math.sin(t * 1.6)];
}

export default function RimGlowButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const targetXRef = useRef<number>(0) as Box<number>;
  const targetYRef = useRef<number>(0) as Box<number>;
  const curXRef = useRef<number>(0) as Box<number>;
  const curYRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(nx: number, ny: number): void {
    const btn = btnRef.current;
    if (!btn) return;
    btn.style.transform = "rotateX(" + (-ny * MAX_DEG).toFixed(2) + "deg) rotateY(" + (nx * MAX_DEG).toFixed(2) + "deg)";
    const mag = clamp(Math.sqrt(nx * nx + ny * ny), 0, 1);
    const blur = BLUR_BASE + mag * BLUR_RANGE;
    const spread = 1 + mag * 5;
    const alpha = (0.28 + mag * 0.5).toFixed(2);
    btn.style.boxShadow = "0 0 " + blur.toFixed(1) + "px " + spread.toFixed(1) + "px rgba(91,140,248," + alpha + "), 0 12px 20px rgba(23,20,26,.28)";
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(0.5, 0.4);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      if (!hasPointerRef.current) {
        const s = syntheticTarget(t);
        targetXRef.current = s[0];
        targetYRef.current = s[1];
      }
      curXRef.current += (targetXRef.current - curXRef.current) * LERP;
      curYRef.current += (targetYRef.current - curYRef.current) * LERP;
      render(curXRef.current, curYRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function pointFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const nx = ((event.clientX - r.left) / r.width) * 2 - 1;
    const ny = ((event.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const p = pointFromEvent(event);
    targetXRef.current = p[0];
    targetYRef.current = p[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
    targetXRef.current = 0;
    targetYRef.current = 0;
  }

  function onClick(): void {
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = 0.95;
    targetYRef.current = 0.3;
    if (reduce) render(targetXRef.current, targetYRef.current);
    window.setTimeout(() => {
      if (!hasPointerRef.current) {
        targetXRef.current = 0;
        targetYRef.current = 0;
        if (reduce) render(targetXRef.current, targetYRef.current);
      }
    }, 240);
  }

  function onKeyDown(event: KeyEvt): void {
    const step = 0.24;
    const moves: { [key: string]: [number, number] } = {
      ArrowLeft: [-step, 0],
      ArrowRight: [step, 0],
      ArrowUp: [0, -step],
      ArrowDown: [0, step],
    };
    const m = moves[event.key];
    if (!m) return;
    event.preventDefault();
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = clamp(targetXRef.current + m[0], -1, 1);
    targetYRef.current = clamp(targetYRef.current + m[1], -1, 1);
    if (reduce) render(targetXRef.current, targetYRef.current);
  }

  const cls = [styles.rg, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>기울기 크기(방향과 무관)만 골라 둘레 전체의 광 반경·밝기로 바꿉니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <button className={styles.btn} ref={btnRef} type="button" aria-label={LABEL} onClick={onClick} onKeyDown={onKeyDown}>
            <span className={styles.label}>지금 플레이</span>
          </button>
        </div>
      </div>
    </main>
  );
}

<main class="stage">
<div class="id is-demo" id="idw">
  <p class="id__hint"><span>주파수가 다른 사인파 둘을 더해 손을 떼도 버튼이 스스로 천천히 떠돕니다</span></p>
  <div class="id__scene" id="scene">
    <span class="id__floor" id="floor" aria-hidden="true"></span>
    <button class="id__btn" id="btn" type="button" aria-label="무료로 시작하기 — 가만히 둬도 떠도는 버튼">
      <span class="id__glow" id="glow" aria-hidden="true"></span>
      <span class="id__label">무료로 시작하기</span>
    </button>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-ink);

.id {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.id__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba($subject-cream, .78);
}

.id__scene {
  position: relative;
  perspective: 640px;
  padding: $sp-6;
}

// 바닥 그림자 — 기운 반대쪽으로 옮겨가며 면적을 만든다
.id__floor {
  position: absolute;
  left: 50%;
  bottom: 2px;
  width: clamp(130px, 46vw, 220px);
  height: clamp(38px, 13.4vw, 64px);
  margin-left: clamp(-110px, -23vw, -65px);
  border-radius: 50%;
  background: radial-gradient(closest-side, rgba($stage-ink, .72), rgba($stage-ink, 0) 72%);
  filter: blur(10px);
  pointer-events: none;
}

.id__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: $sp-5 $sp-12;
  border-radius: $r-pill;
  background: $subject-blue-deep;
  color: $subject-cream;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  overflow: hidden;
  will-change: transform, box-shadow;
}

.id__btn:focus-visible {
  outline: 2px solid $subject-cream;
  outline-offset: 3px;
}

// 하이라이트 — 그림자와 짝으로 기운 반대쪽에서 밝아진다
.id__glow {
  position: absolute;
  inset: 0;
  border-radius: inherit;
  pointer-events: none;
}

.id__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .id__btn { transition: none; }
}

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);
}

.id {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.id__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: rgba(255, 247, 230, 0.78);
}

.id__scene {
  position: relative;
  perspective: 640px;
  padding: 24px;
}

.id__floor {
  position: absolute;
  left: 50%;
  bottom: 2px;
  width: clamp(130px, 46vw, 220px);
  height: clamp(38px, 13.4vw, 64px);
  margin-left: clamp(-110px, -23vw, -65px);
  border-radius: 50%;
  background: radial-gradient(closest-side, rgba(23, 20, 26, 0.72), rgba(23, 20, 26, 0) 72%);
  filter: blur(10px);
  pointer-events: none;
}

.id__btn {
  position: relative;
  border: 0;
  cursor: pointer;
  padding: 20px 48px;
  border-radius: 999px;
  background: #0a4fe8;
  color: #fff7e6;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  overflow: hidden;
  will-change: transform, box-shadow;
}

.id__btn:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 3px;
}

.id__glow {
  position: absolute;
  inset: 0;
  border-radius: inherit;
  pointer-events: none;
}

.id__label {
  position: relative;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .id__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('idw');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var floor = document.getElementById('floor');
  var glow = document.getElementById('glow');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var MAX_DEG = 8;   // 불변
  var LERP = 0.12;
  var targetNX = 0, targetNY = 0, curNX = 0, curNY = 0;
  var hasPointer = false;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }

  // 유휴 드리프트 — 주파수·위상이 다른 사인파 둘을 더한 합성 곡선(고정 시드). 포인터가 있으면 좌표로 덮인다
  // 진폭 상수를 키워 자동 시연에서도 가장자리(±1, MAX_DEG 전체)까지 실제로 닿게 한다
  function idleDrift(t) {
    var x = 0.85 * Math.sin(t * 0.55) + 0.55 * Math.sin(t * 1.31 + 0.8);
    var y = 0.76 * Math.sin(t * 0.41 + 1.3) + 0.48 * Math.sin(t * 0.97 + 2.4);
    return [clamp(x, -1, 1), clamp(y, -1, 1)];
  }

  function render(nx, ny) {
    var rotY = nx * MAX_DEG;
    var rotX = -ny * MAX_DEG;
    var mag = Math.min(1, Math.sqrt(nx * nx + ny * ny));
    var lift = 1 - mag * 0.4;
    btn.style.transform = 'translateY(' + ((1 - lift) * -6).toFixed(2) + 'px) rotateX(' + rotX.toFixed(2) + 'deg) rotateY(' + rotY.toFixed(2) + 'deg)';
    var blur = 16 + Math.abs(nx) * 10 + Math.abs(ny) * 10;
    btn.style.boxShadow = '0 ' + (10 * lift).toFixed(1) + 'px ' + blur.toFixed(1) + 'px rgba(8,6,12,.34)';
    // 바닥 그림자 — 기운 반대쪽으로 떨어져 나가며 면적을 만든다
    floor.style.transform = 'translate(' + (nx * 38).toFixed(1) + 'px, ' + (ny * 16).toFixed(1) + 'px) scale(' + (1 + mag * 0.32).toFixed(2) + ')';
    floor.style.opacity = (0.16 + mag * 0.55).toFixed(2);
    // 하이라이트 — 기운 반대쪽(들린 쪽)에서 밝아져 그림자와 짝으로 움직인다
    var gx = (50 - nx * 32).toFixed(0);
    var gy = (50 - ny * 32).toFixed(0);
    glow.style.background = 'radial-gradient(circle at ' + gx + '% ' + gy + '%, rgba(255,255,255,' + (0.16 + mag * 0.42).toFixed(2) + '), rgba(255,255,255,0) 62%)';
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) t0 = now;
    var t = (now - t0) / 1000;
    if (!hasPointer && !reduce) {
      var d = idleDrift(t);
      targetNX = d[0]; targetNY = d[1];
    }
    curNX += (targetNX - curNX) * LERP;
    curNY += (targetNY - curNY) * LERP;
    render(curNX, curNY);
    requestAnimationFrame(loop);
  }

  function pointFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var nx = ((e.clientX - r.left) / r.width) * 2 - 1;
    var ny = ((e.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var p = pointFromEvent(e);
    targetNX = p[0]; targetNY = p[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = 0; targetNY = -0.9;
    if (reduce) { render(targetNX, targetNY); }
    setTimeout(function () { hasPointer = false; }, 260);
  });
  btn.addEventListener('keydown', function (e) {
    var step = 0.22;
    var moves = { ArrowLeft: [-step, 0], ArrowRight: [step, 0], ArrowUp: [0, -step], ArrowDown: [0, step] };
    var m = moves[e.key];
    if (!m) return;
    e.preventDefault();
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = clamp(targetNX + m[0], -1, 1);
    targetNY = clamp(targetNY + m[1], -1, 1);
    if (reduce) { render(targetNX, targetNY); }
  });

  if (reduce) {
    render(0.2, -0.2);
  } else {
    requestAnimationFrame(loop);
  }
})();

// IdleDriftButton — vanilla 판(run/393/demo/09-pointer-tilt-3d-idle-drift/index.html) 의 React 포트.
// 주파수·위상이 다른 사인파 둘을 더한 합성 곡선(고정 시드)이 유휴 드리프트를 만들고,
// 포인터가 있으면 그 좌표가 목표값을 덮어쓴다. 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./IdleDriftButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const MAX_DEG = 8; // 불변
const LERP = 0.12;
const LABEL = "무료로 시작하기 — 가만히 둬도 떠도는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}
// 진폭 상수를 키워 자동 시연에서도 가장자리(±1, MAX_DEG 전체)까지 실제로 닿게 한다
function idleDrift(t: number): [number, number] {
  const x = 0.85 * Math.sin(t * 0.55) + 0.55 * Math.sin(t * 1.31 + 0.8);
  const y = 0.76 * Math.sin(t * 0.41 + 1.3) + 0.48 * Math.sin(t * 0.97 + 2.4);
  return [clamp(x, -1, 1), clamp(y, -1, 1)];
}

export default function IdleDriftButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const floorRef = useRef<HTMLSpanElement | null>(null);
  const glowRef = useRef<HTMLSpanElement | null>(null);
  const targetXRef = useRef<number>(0) as Box<number>;
  const targetYRef = useRef<number>(0) as Box<number>;
  const curXRef = useRef<number>(0) as Box<number>;
  const curYRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(nx: number, ny: number): void {
    const btn = btnRef.current;
    const floor = floorRef.current;
    const glow = glowRef.current;
    if (!btn || !floor || !glow) return;
    const rotY = nx * MAX_DEG;
    const rotX = -ny * MAX_DEG;
    const mag = Math.min(1, Math.sqrt(nx * nx + ny * ny));
    const lift = 1 - mag * 0.4;
    btn.style.transform = "translateY(" + ((1 - lift) * -6).toFixed(2) + "px) rotateX(" + rotX.toFixed(2) + "deg) rotateY(" + rotY.toFixed(2) + "deg)";
    const blur = 16 + Math.abs(nx) * 10 + Math.abs(ny) * 10;
    btn.style.boxShadow = "0 " + (10 * lift).toFixed(1) + "px " + blur.toFixed(1) + "px rgba(8,6,12,.34)";
    floor.style.transform = "translate(" + (nx * 38).toFixed(1) + "px, " + (ny * 16).toFixed(1) + "px) scale(" + (1 + mag * 0.32).toFixed(2) + ")";
    floor.style.opacity = (0.16 + mag * 0.55).toFixed(2);
    const gx = (50 - nx * 32).toFixed(0);
    const gy = (50 - ny * 32).toFixed(0);
    glow.style.background = "radial-gradient(circle at " + gx + "% " + gy + "%, rgba(255,255,255," + (0.16 + mag * 0.42).toFixed(2) + "), rgba(255,255,255,0) 62%)";
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(0.2, -0.2);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      if (!hasPointerRef.current) {
        const d = idleDrift(t);
        targetXRef.current = d[0];
        targetYRef.current = d[1];
      }
      curXRef.current += (targetXRef.current - curXRef.current) * LERP;
      curYRef.current += (targetYRef.current - curYRef.current) * LERP;
      render(curXRef.current, curYRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function pointFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const nx = ((event.clientX - r.left) / r.width) * 2 - 1;
    const ny = ((event.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const p = pointFromEvent(event);
    targetXRef.current = p[0];
    targetYRef.current = p[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
  }

  function onClick(): void {
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = 0;
    targetYRef.current = -0.9;
    if (reduce) render(targetXRef.current, targetYRef.current);
    window.setTimeout(() => {
      hasPointerRef.current = false;
    }, 260);
  }

  function onKeyDown(event: KeyEvt): void {
    const step = 0.22;
    const moves: { [key: string]: [number, number] } = {
      ArrowLeft: [-step, 0],
      ArrowRight: [step, 0],
      ArrowUp: [0, -step],
      ArrowDown: [0, step],
    };
    const m = moves[event.key];
    if (!m) return;
    event.preventDefault();
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = clamp(targetXRef.current + m[0], -1, 1);
    targetYRef.current = clamp(targetYRef.current + m[1], -1, 1);
    if (reduce) render(targetXRef.current, targetYRef.current);
  }

  const cls = [styles.id, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>주파수가 다른 사인파 둘을 더해 손을 떼도 버튼이 스스로 천천히 떠돕니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <span className={styles.floor} ref={floorRef} aria-hidden="true" />
          <button className={styles.btn} ref={btnRef} type="button" aria-label={LABEL} onClick={onClick} onKeyDown={onKeyDown}>
            <span className={styles.glow} ref={glowRef} aria-hidden="true" />
            <span className={styles.label}>무료로 시작하기</span>
          </button>
        </div>
      </div>
    </main>
  );
}