04Button a Depth Value Pushes Only the Icon Apart

<main class="stage">
<div class="ip is-demo" id="ip">
  <p class="ip__hint"><span>The same coordinates are multiplied by a different factor per layer, so the icon moves further than the label</span></p>
  <div class="ip__scene" id="scene">
    <button class="ip__btn" id="btn" type="button" aria-label="Download — button whose icon parallaxes on the front layer">
      <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">Download</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>
  );
}