03경계 밖으로 밀면 늘어났다 되돌아오는 고무 바운더리

<main class="stage">
<div class="br is-demo" id="br">
  <div class="br__box" id="brBox">
    <button type="button" class="br__icon" id="brIcon" aria-label="경계 안에서만 움직이는 아이콘. 경계를 넘으면 고무처럼 늘어납니다. Enter 로 잡고 화살표로 이동, Enter 로 놓습니다"></button>
  </div>
  <p class="br__caption" id="brCaption">경계 밖으로 밀면 고무처럼 눌려요</p>
</div>
</main>

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

.br {
  position: relative;
  width: min(92vw, calc(160vh - 12.8vw));
  max-width: 400px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-4;
}

.br__box {
  position: relative;
  width: 100%;
  height: 140px;
  max-width: 300px;
  border-radius: $r-card;
  border: 2px dashed rgba($subject-ink, .28);
  display: flex;
  align-items: center;
  justify-content: center;
}

.br__icon {
  appearance: none;
  border: 0;
  width: 52px;
  height: 52px;
  border-radius: $r-pill;
  background: $subject-blue;
  box-shadow: $shadow-raised;
  cursor: grab;
  touch-action: none;
  will-change: transform;
}

.br.is-stretch .br__icon {
  background: $subject-blue-deep;
}

.br__icon.is-grabbed,
.br__icon:focus-visible {
  outline: 2px solid $subject-blue-light;
  outline-offset: 3px;
}

.br.is-dragging .br__icon {
  cursor: grabbing;
}

.br__caption {
  margin: 0;
  color: $subject-ink;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  text-align: center;
}

@media (max-width: 340px) {
  .br__box { height: 108px; }
  .br__icon { width: 40px; height: 40px; }
  .br__caption { font-size: 10px; }
}

@media (prefers-reduced-motion: reduce) {
  .br__icon { 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);
}

.br {
  position: relative;
  width: min(92vw, 160vh - 12.8vw);
  max-width: 400px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.br__box {
  position: relative;
  width: 100%;
  height: 140px;
  max-width: 300px;
  border-radius: 16px;
  border: 2px dashed rgba(23, 20, 26, 0.28);
  display: flex;
  align-items: center;
  justify-content: center;
}

.br__icon {
  appearance: none;
  border: 0;
  width: 52px;
  height: 52px;
  border-radius: 999px;
  background: #2f6df6;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  cursor: grab;
  touch-action: none;
  will-change: transform;
}

.br.is-stretch .br__icon {
  background: #0a4fe8;
}

.br__icon.is-grabbed,
.br__icon:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 3px;
}

.br.is-dragging .br__icon {
  cursor: grabbing;
}

.br__caption {
  margin: 0;
  color: #17141a;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  text-align: center;
}

@media (max-width: 340px) {
  .br__box {
    height: 108px;
  }
  .br__icon {
    width: 40px;
    height: 40px;
  }
  .br__caption {
    font-size: 10px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .br__icon {
    transition: none;
  }
}

(function () {
  // 기법: 아이콘이 경계 상자 밖으로 나간 거리(overflow)를 축별로 계산해
  // BOUNDARY_RUBBER_MAX_PX 로 클램프한 뒤, 그 비율만큼 scale·skew 를 섞어
  // "눌린" 모양을 만들고, 손을 떼면 감쇠 스프링으로 경계 안쪽까지 되돌린다.
  var root = document.getElementById('br');
  var box = document.getElementById('brBox');
  var icon = document.getElementById('brIcon');
  var caption = document.getElementById('brCaption');

  var BOUNDARY_RUBBER_MAX_PX = 40;
  var BOUNDARY_SPRING_STIFFNESS = 200;
  var BOUNDARY_SPRING_DAMPING = 20;
  var KEY_STEP_PX = 16;

  var pos = { x: 0, y: 0 };
  var vel = { x: 0, y: 0 };
  var grabbed = false;
  var pointerStart = null;
  var startPos = null;
  var raf = 0, lastTs = null;

  function bounds() {
    var br = box.getBoundingClientRect();
    var ir = icon.getBoundingClientRect();
    var halfW = ir.width / 2, halfH = ir.height / 2;
    return {
      minX: br.left + halfW, maxX: br.right - halfW,
      minY: br.top + halfH, maxY: br.bottom - halfH
    };
  }

  function overflowOf(clientX, clientY) {
    var b = bounds();
    var ox = 0, oy = 0;
    if (clientX < b.minX) ox = clientX - b.minX;
    else if (clientX > b.maxX) ox = clientX - b.maxX;
    if (clientY < b.minY) oy = clientY - b.minY;
    else if (clientY > b.maxY) oy = clientY - b.maxY;
    return { x: ox, y: oy };
  }

  function applyVisual(clampedX, clampedY, overflow) {
    var ratioX = Math.min(1, Math.abs(overflow.x) / BOUNDARY_RUBBER_MAX_PX);
    var ratioY = Math.min(1, Math.abs(overflow.y) / BOUNDARY_RUBBER_MAX_PX);
    var ratio = Math.max(ratioX, ratioY);
    var scaleStretch = 1 + ratio * 0.28;
    var scaleSquash = 1 - ratio * 0.22;
    var skewX = overflow.x !== 0 ? (overflow.x > 0 ? 1 : -1) * ratioX * 6 : 0;
    var skewY = overflow.y !== 0 ? (overflow.y > 0 ? 1 : -1) * ratioY * 6 : 0;
    var sx = ratioX >= ratioY ? scaleStretch : scaleSquash;
    var sy = ratioY >= ratioX ? scaleStretch : scaleSquash;
    icon.style.transform = 'translate(' + clampedX.toFixed(1) + 'px,' + clampedY.toFixed(1) + 'px) scale(' + sx.toFixed(3) + ',' + sy.toFixed(3) + ') skew(' + skewX.toFixed(2) + 'deg,' + skewY.toFixed(2) + 'deg)';
    root.classList.toggle('is-stretch', ratio > 0.02);
  }

  function settleTick(ts) {
    if (lastTs === null) lastTs = ts;
    var dt = Math.min((ts - lastTs) / 1000, 0.032);
    lastTs = ts;
    var fx = (0 - pos.x) * BOUNDARY_SPRING_STIFFNESS - vel.x * BOUNDARY_SPRING_DAMPING;
    var fy = (0 - pos.y) * BOUNDARY_SPRING_STIFFNESS - vel.y * BOUNDARY_SPRING_DAMPING;
    vel.x += fx * dt; vel.y += fy * dt;
    pos.x += vel.x * dt; pos.y += vel.y * dt;
    applyVisual(pos.x, pos.y, { x: 0, y: 0 });
    var rest = Math.hypot(vel.x, vel.y) < 2 && Math.hypot(pos.x, pos.y) < 0.6;
    if (!rest) { raf = requestAnimationFrame(settleTick); return; }
    pos.x = 0; pos.y = 0; vel.x = 0; vel.y = 0;
    applyVisual(0, 0, { x: 0, y: 0 });
    lastTs = null;
  }

  function springHome() {
    cancelAnimationFrame(raf);
    lastTs = null;
    raf = requestAnimationFrame(settleTick);
  }

  function beginDrag(clientX, clientY) {
    cancelAnimationFrame(raf);
    vel.x = 0; vel.y = 0;
    pointerStart = { x: clientX, y: clientY };
    startPos = { x: pos.x, y: pos.y };
    root.classList.add('is-dragging');
  }

  function moveDrag(clientX, clientY) {
    var rawX = startPos.x + (clientX - pointerStart.x);
    var rawY = startPos.y + (clientY - pointerStart.y);
    var iconRect = icon.getBoundingClientRect();
    var curCx = iconRect.left + iconRect.width / 2;
    var curCy = iconRect.top + iconRect.height / 2;
    var moveX = clientX - pointerStart.x;
    var moveY = clientY - pointerStart.y;
    var wantCx = curCx - (pos.x - rawX);
    var wantCy = curCy - (pos.y - rawY);
    var overflow = overflowOf(wantCx, wantCy);
    var clampedOverX = Math.max(-BOUNDARY_RUBBER_MAX_PX, Math.min(BOUNDARY_RUBBER_MAX_PX, overflow.x));
    var clampedOverY = Math.max(-BOUNDARY_RUBBER_MAX_PX, Math.min(BOUNDARY_RUBBER_MAX_PX, overflow.y));
    var clampX = rawX - (overflow.x - clampedOverX);
    var clampY = rawY - (overflow.y - clampedOverY);
    pos.x = clampX; pos.y = clampY;
    applyVisual(pos.x, pos.y, { x: clampedOverX, y: clampedOverY });
    if (Math.abs(clampedOverX) > 2 || Math.abs(clampedOverY) > 2) {
      caption.textContent = '더 밀면 늘어남이 커져요 (한도 있음)';
    } else {
      caption.textContent = '경계 밖으로 밀면 고무처럼 눌려요';
    }
  }

  function endDrag() {
    root.classList.remove('is-dragging');
    root.classList.remove('is-stretch');
    var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
    caption.textContent = '경계 밖으로 밀면 고무처럼 눌려요';
    if (reduce) { pos.x = 0; pos.y = 0; applyVisual(0, 0, { x: 0, y: 0 }); }
    else { springHome(); }
  }

  icon.addEventListener('pointerdown', function (e) {
    root.classList.remove('is-demo');
    icon.setPointerCapture(e.pointerId);
    beginDrag(e.clientX, e.clientY);
    e.preventDefault();
  });
  icon.addEventListener('pointermove', function (e) {
    if (!pointerStart) return;
    moveDrag(e.clientX, e.clientY);
    e.preventDefault();
  });
  icon.addEventListener('pointerup', function (e) {
    if (!pointerStart) return;
    pointerStart = null;
    endDrag();
    e.preventDefault();
  });

  icon.addEventListener('keydown', function (e) {
    root.classList.remove('is-demo');
    if (e.key === 'Enter' || e.key === ' ') {
      e.preventDefault();
      if (!grabbed) {
        grabbed = true;
        cancelAnimationFrame(raf);
        icon.classList.add('is-grabbed');
        caption.textContent = '잡았어요. 화살표로 밀고 Enter 로 놓으세요';
      } else {
        grabbed = false;
        icon.classList.remove('is-grabbed');
        endDrag();
      }
      return;
    }
    if (!grabbed) return;
    var dx = 0, dy = 0;
    if (e.key === 'ArrowLeft') dx = -KEY_STEP_PX;
    else if (e.key === 'ArrowRight') dx = KEY_STEP_PX;
    else if (e.key === 'ArrowUp') dy = -KEY_STEP_PX;
    else if (e.key === 'ArrowDown') dy = KEY_STEP_PX;
    else if (e.key === 'Escape') {
      e.preventDefault();
      grabbed = false;
      icon.classList.remove('is-grabbed');
      endDrag();
      return;
    } else { return; }
    e.preventDefault();
    var iconRect = icon.getBoundingClientRect();
    var wantCx = iconRect.left + iconRect.width / 2 + dx;
    var wantCy = iconRect.top + iconRect.height / 2 + dy;
    var overflow = overflowOf(wantCx, wantCy);
    var clampedOverX = Math.max(-BOUNDARY_RUBBER_MAX_PX, Math.min(BOUNDARY_RUBBER_MAX_PX, overflow.x));
    var clampedOverY = Math.max(-BOUNDARY_RUBBER_MAX_PX, Math.min(BOUNDARY_RUBBER_MAX_PX, overflow.y));
    pos.x += dx - (overflow.x - clampedOverX);
    pos.y += dy - (overflow.y - clampedOverY);
    applyVisual(pos.x, pos.y, { x: clampedOverX, y: clampedOverY });
  });

  applyVisual(0, 0, { x: 0, y: 0 });

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (reduce) {
    root.classList.remove('is-demo');
  } else {
    var iconRect0 = icon.getBoundingClientRect();
    var ox0 = iconRect0.left + iconRect0.width / 2;
    var oy0 = iconRect0.top + iconRect0.height / 2;
    var pushX = ox0 + 130, pushY = oy0;
    var demoStart = null;
    function demoTick(ts) {
      if (demoStart === null) demoStart = ts;
      var t = ts - demoStart;
      if (t < 200) {
        // 대기
      } else if (t < 900) {
        var p = Math.min(1, (t - 200) / 700);
        var ease = 1 - Math.pow(1 - p, 2);
        var cx = ox0 + (pushX - ox0) * ease;
        if (t < 220) beginDrag(ox0, oy0);
        moveDrag(cx, pushY);
      } else if (t < 1150) {
        // 눌린 모양 관찰
      } else if (t < 1180) {
        endDrag();
      } else {
        if (t > 1900) demoStart = ts - 60;
      }
      requestAnimationFrame(demoTick);
    }
    requestAnimationFrame(demoTick);
  }
})();

import { useEffect, useRef } from "react";
import styles from "./DragPhysBoundaryRubber.module.scss";

type Box<T> = { current: T };
type Pt = { x: number; y: number };

export default function DragPhysBoundaryRubber() {
  const rootRef = useRef<HTMLDivElement>(null);
  const boxRef = useRef<HTMLDivElement>(null);
  const iconRef = useRef<HTMLButtonElement>(null);
  const captionRef = useRef<HTMLParagraphElement>(null);

  useEffect(() => {
    const root = rootRef.current;
    const box = boxRef.current;
    const icon = iconRef.current;
    const caption = captionRef.current;
    if (!root || !box || !icon || !caption) return;

    const BOUNDARY_RUBBER_MAX_PX = 40;
    const BOUNDARY_SPRING_STIFFNESS = 200;
    const BOUNDARY_SPRING_DAMPING = 20;
    const KEY_STEP_PX = 16;

    const pos: Pt = { x: 0, y: 0 };
    const vel: Pt = { x: 0, y: 0 };
    let grabbed = false;
    let pointerStart: Pt | null = null;
    let startPos: Pt = { x: 0, y: 0 };
    let raf = 0, lastTs: number | null = null;

    function bounds() {
      const br = box!.getBoundingClientRect();
      const ir = icon!.getBoundingClientRect();
      const halfW = ir.width / 2, halfH = ir.height / 2;
      return {
        minX: br.left + halfW, maxX: br.right - halfW,
        minY: br.top + halfH, maxY: br.bottom - halfH,
      };
    }

    function overflowOf(clientX: number, clientY: number) {
      const b = bounds();
      let ox = 0, oy = 0;
      if (clientX < b.minX) ox = clientX - b.minX;
      else if (clientX > b.maxX) ox = clientX - b.maxX;
      if (clientY < b.minY) oy = clientY - b.minY;
      else if (clientY > b.maxY) oy = clientY - b.maxY;
      return { x: ox, y: oy };
    }

    function applyVisual(clampedX: number, clampedY: number, overflow: Pt) {
      const ratioX = Math.min(1, Math.abs(overflow.x) / BOUNDARY_RUBBER_MAX_PX);
      const ratioY = Math.min(1, Math.abs(overflow.y) / BOUNDARY_RUBBER_MAX_PX);
      const ratio = Math.max(ratioX, ratioY);
      const scaleStretch = 1 + ratio * 0.28;
      const scaleSquash = 1 - ratio * 0.22;
      const skewX = overflow.x !== 0 ? (overflow.x > 0 ? 1 : -1) * ratioX * 6 : 0;
      const skewY = overflow.y !== 0 ? (overflow.y > 0 ? 1 : -1) * ratioY * 6 : 0;
      const sx = ratioX >= ratioY ? scaleStretch : scaleSquash;
      const sy = ratioY >= ratioX ? scaleStretch : scaleSquash;
      icon!.style.transform =
        "translate(" + clampedX.toFixed(1) + "px," + clampedY.toFixed(1) + "px) scale(" +
        sx.toFixed(3) + "," + sy.toFixed(3) + ") skew(" + skewX.toFixed(2) + "deg," + skewY.toFixed(2) + "deg)";
      root!.classList.toggle(styles.isStretch, ratio > 0.02);
    }

    function settleTick(ts: number) {
      if (lastTs === null) lastTs = ts;
      const dt = Math.min((ts - lastTs) / 1000, 0.032);
      lastTs = ts;
      const fx = (0 - pos.x) * BOUNDARY_SPRING_STIFFNESS - vel.x * BOUNDARY_SPRING_DAMPING;
      const fy = (0 - pos.y) * BOUNDARY_SPRING_STIFFNESS - vel.y * BOUNDARY_SPRING_DAMPING;
      vel.x += fx * dt; vel.y += fy * dt;
      pos.x += vel.x * dt; pos.y += vel.y * dt;
      applyVisual(pos.x, pos.y, { x: 0, y: 0 });
      const rest = Math.hypot(vel.x, vel.y) < 2 && Math.hypot(pos.x, pos.y) < 0.6;
      if (!rest) { raf = requestAnimationFrame(settleTick); return; }
      pos.x = 0; pos.y = 0; vel.x = 0; vel.y = 0;
      applyVisual(0, 0, { x: 0, y: 0 });
      lastTs = null;
    }

    function springHome() {
      cancelAnimationFrame(raf);
      lastTs = null;
      raf = requestAnimationFrame(settleTick);
    }

    function beginDrag(clientX: number, clientY: number) {
      cancelAnimationFrame(raf);
      vel.x = 0; vel.y = 0;
      pointerStart = { x: clientX, y: clientY };
      startPos = { x: pos.x, y: pos.y };
      root!.classList.add(styles.isDragging);
    }

    function moveDrag(clientX: number, clientY: number) {
      const rawX = startPos.x + (clientX - pointerStart!.x);
      const rawY = startPos.y + (clientY - pointerStart!.y);
      const iconRect = icon!.getBoundingClientRect();
      const curCx = iconRect.left + iconRect.width / 2;
      const curCy = iconRect.top + iconRect.height / 2;
      const wantCx = curCx - (pos.x - rawX);
      const wantCy = curCy - (pos.y - rawY);
      const overflow = overflowOf(wantCx, wantCy);
      const clampedOverX = Math.max(-BOUNDARY_RUBBER_MAX_PX, Math.min(BOUNDARY_RUBBER_MAX_PX, overflow.x));
      const clampedOverY = Math.max(-BOUNDARY_RUBBER_MAX_PX, Math.min(BOUNDARY_RUBBER_MAX_PX, overflow.y));
      const clampX = rawX - (overflow.x - clampedOverX);
      const clampY = rawY - (overflow.y - clampedOverY);
      pos.x = clampX; pos.y = clampY;
      applyVisual(pos.x, pos.y, { x: clampedOverX, y: clampedOverY });
      if (Math.abs(clampedOverX) > 2 || Math.abs(clampedOverY) > 2) {
        caption!.textContent = "더 밀면 늘어남이 커져요 (한도 있음)";
      } else {
        caption!.textContent = "경계 밖으로 밀면 고무처럼 눌려요";
      }
    }

    function endDrag() {
      root!.classList.remove(styles.isDragging);
      root!.classList.remove(styles.isStretch);
      const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
      caption!.textContent = "경계 밖으로 밀면 고무처럼 눌려요";
      if (reduce) { pos.x = 0; pos.y = 0; applyVisual(0, 0, { x: 0, y: 0 }); } else { springHome(); }
    }

    function onPointerDown(e: PointerEvent) {
      root!.classList.remove("is-demo");
      icon!.setPointerCapture(e.pointerId);
      beginDrag(e.clientX, e.clientY);
      e.preventDefault();
    }
    function onPointerMove(e: PointerEvent) {
      if (!pointerStart) return;
      moveDrag(e.clientX, e.clientY);
      e.preventDefault();
    }
    function onPointerUp(e: PointerEvent) {
      if (!pointerStart) return;
      pointerStart = null;
      endDrag();
      e.preventDefault();
    }
    icon.addEventListener("pointerdown", onPointerDown);
    icon.addEventListener("pointermove", onPointerMove);
    icon.addEventListener("pointerup", onPointerUp);

    function onKeyDown(e: KeyboardEvent) {
      root!.classList.remove("is-demo");
      if (e.key === "Enter" || e.key === " ") {
        e.preventDefault();
        if (!grabbed) {
          grabbed = true;
          cancelAnimationFrame(raf);
          icon!.classList.add(styles.isGrabbed);
          caption!.textContent = "잡았어요. 화살표로 밀고 Enter 로 놓으세요";
        } else {
          grabbed = false;
          icon!.classList.remove(styles.isGrabbed);
          endDrag();
        }
        return;
      }
      if (!grabbed) return;
      let dx = 0, dy = 0;
      if (e.key === "ArrowLeft") dx = -KEY_STEP_PX;
      else if (e.key === "ArrowRight") dx = KEY_STEP_PX;
      else if (e.key === "ArrowUp") dy = -KEY_STEP_PX;
      else if (e.key === "ArrowDown") dy = KEY_STEP_PX;
      else if (e.key === "Escape") {
        e.preventDefault();
        grabbed = false;
        icon!.classList.remove(styles.isGrabbed);
        endDrag();
        return;
      } else { return; }
      e.preventDefault();
      const iconRect = icon!.getBoundingClientRect();
      const wantCx = iconRect.left + iconRect.width / 2 + dx;
      const wantCy = iconRect.top + iconRect.height / 2 + dy;
      const overflow = overflowOf(wantCx, wantCy);
      const clampedOverX = Math.max(-BOUNDARY_RUBBER_MAX_PX, Math.min(BOUNDARY_RUBBER_MAX_PX, overflow.x));
      const clampedOverY = Math.max(-BOUNDARY_RUBBER_MAX_PX, Math.min(BOUNDARY_RUBBER_MAX_PX, overflow.y));
      pos.x += dx - (overflow.x - clampedOverX);
      pos.y += dy - (overflow.y - clampedOverY);
      applyVisual(pos.x, pos.y, { x: clampedOverX, y: clampedOverY });
    }
    icon.addEventListener("keydown", onKeyDown);

    applyVisual(0, 0, { x: 0, y: 0 });

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    let demoRaf = 0;
    if (reduce) {
      root.classList.remove("is-demo");
    } else {
      const iconRect0 = icon.getBoundingClientRect();
      const ox0 = iconRect0.left + iconRect0.width / 2;
      const oy0 = iconRect0.top + iconRect0.height / 2;
      const pushX = ox0 + 130, pushY = oy0;
      let demoStart: number | null = null;
      function demoTick(ts: number) {
        if (demoStart === null) demoStart = ts;
        const t = ts - demoStart;
        if (t < 200) {
          // 대기
        } else if (t < 900) {
          const p = Math.min(1, (t - 200) / 700);
          const ease = 1 - Math.pow(1 - p, 2);
          const cx = ox0 + (pushX - ox0) * ease;
          if (t < 220) beginDrag(ox0, oy0);
          moveDrag(cx, pushY);
        } else if (t < 1150) {
          // 눌린 모양 관찰
        } else if (t < 1180) {
          endDrag();
        } else {
          if (t > 1900) demoStart = ts - 60;
        }
        demoRaf = requestAnimationFrame(demoTick);
      }
      demoRaf = requestAnimationFrame(demoTick);
    }

    return () => {
      icon.removeEventListener("pointerdown", onPointerDown);
      icon.removeEventListener("pointermove", onPointerMove);
      icon.removeEventListener("pointerup", onPointerUp);
      icon.removeEventListener("keydown", onKeyDown);
      cancelAnimationFrame(raf);
      cancelAnimationFrame(demoRaf);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={`${styles.br} is-demo`} ref={rootRef}>
        <div className={styles.box} ref={boxRef}>
          <button
            type="button"
            className={styles.icon}
            ref={iconRef}
            aria-label="경계 안에서만 움직이는 아이콘. 경계를 넘으면 고무처럼 늘어납니다. Enter 로 잡고 화살표로 이동, Enter 로 놓습니다"
          ></button>
        </div>
        <p className={styles.caption} ref={captionRef}>경계 밖으로 밀면 고무처럼 눌려요</p>
      </div>
    </main>
  );
}