09Rounded corner comparison — a card placing a circular-arc corner next to a smooth squircle corner

<main class="stage">
<div class="wrap is-demo" id="wrap">
  <span class="supportBadge" id="supportBadge">Checking</span>
  <div class="cards">
    <div class="cardCol">
      <span class="colLabel">border-radius default arc</span>
      <div class="card cardRadius" id="cardRadius"></div>
    </div>
    <div class="cardCol">
      <span class="colLabel">One line added: corner-shape</span>
      <div class="card cardShape" id="cardShape"></div>
    </div>
  </div>
  <div class="readout" id="readout">Radius —px</div>
</div>
</main>

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

// 계산 겹은 index.html 의 apply() 에 있다 — 클릭·자동 루프가 같은 반경 값을 두 카드에 동시에
// 넣고 getComputedStyle 로 실제 렌더 결과를 다시 읽는다. corner-shape 는 여기 CSS 한 줄로만
// 오른쪽 카드에 더해진다 — @supports 안에 있어 미지원 환경은 자동으로 원호 폴백이다.
@include stage($stage-ink);

.wrap {
  width: 300px;
  display: flex;
  flex-direction: column;
  gap: $sp-3;
  align-items: center;
}

.supportBadge {
  align-self: flex-start;
  color: $subject-cream;
  font-size: 10px;
  font-weight: 600;
  background: rgba($subject-cream, .12);
  border-radius: $r-xs;
  padding: $sp-1 $sp-2;

  &.fallback { background: rgba($subject-orange-deep, .5); }
}

.cards {
  display: flex;
  gap: $sp-3;
}

.cardCol {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-2;
}

.colLabel {
  color: $subject-cream;
  font-size: 10px;
  font-weight: 600;
  text-align: center;
  width: 120px;
}

.card {
  width: 100px;
  height: 100px;
  background: $subject-orange-deep;
  cursor: pointer;
  transition: border-radius $dur-base $ease-out;
}

// 주인공 — border-radius 는 두 카드에 똑같이 JS 로 들어간다. corner-shape 만 오른쪽에 한 줄 더 얹는다.
@supports (corner-shape: squircle) {
  .cardShape {
    corner-shape: squircle;
  }
}

.readout {
  color: $subject-cream;
  font-size: 11px;
}

@media (max-width: 340px) {
  .wrap { width: 260px; gap: $sp-2; }
  .cards { gap: $sp-2; }
  .card { width: 72px; height: 72px; }
  .colLabel { width: 90px; }
}

@media (prefers-reduced-motion: reduce) {
  // reduce: 자동 루프·클릭 전환의 완만함만 지운다(반경 값 자체는 그대로 바뀐다)
  .card { 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);
}

.wrap {
  width: 300px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  align-items: center;
}

.supportBadge {
  align-self: flex-start;
  color: #fff7e6;
  font-size: 10px;
  font-weight: 600;
  background: rgba(255, 247, 230, 0.12);
  border-radius: 4px;
  padding: 4px 8px;
}
.supportBadge.fallback {
  background: rgba(201, 48, 0, 0.5);
}

.cards {
  display: flex;
  gap: 12px;
}

.cardCol {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

.colLabel {
  color: #fff7e6;
  font-size: 10px;
  font-weight: 600;
  text-align: center;
  width: 120px;
}

.card {
  width: 100px;
  height: 100px;
  background: #c93000;
  cursor: pointer;
  transition: border-radius 300ms ease-out;
}

@supports (corner-shape: squircle) {
  .cardShape {
    corner-shape: squircle;
  }
}
.readout {
  color: #fff7e6;
  font-size: 11px;
}

@media (max-width: 340px) {
  .wrap {
    width: 260px;
    gap: 8px;
  }
  .cards {
    gap: 8px;
  }
  .card {
    width: 72px;
    height: 72px;
  }
  .colLabel {
    width: 90px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .card {
    transition: none;
  }
}

(function () {
  var STEP_MS = 900;
  var MIN_R = 10;
  var MAX_R = 34;
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  // corner-shape 는 border-radius 옆에 한 줄만 더하면 되는 값이라 실제로 그렇게 확인한다(추측 금지)
  var supported = typeof CSS !== 'undefined' && CSS.supports && CSS.supports('corner-shape', 'squircle');

  var wrap = document.getElementById('wrap');
  var supportBadge = document.getElementById('supportBadge');
  var cardRadius = document.getElementById('cardRadius');
  var cardShape = document.getElementById('cardShape');
  var readout = document.getElementById('readout');
  var isDemo = true;
  var r = MIN_R;

  supportBadge.textContent = supported ? 'corner-shape supported' : 'Not supported — right side falls back to an arc automatically';
  supportBadge.classList.toggle('fallback', !supported);

  function apply() {
    var px = Math.round(r) + 'px';
    cardRadius.style.borderRadius = px;
    cardShape.style.borderRadius = px;
    // 실측 — 실제로 렌더된 border-radius 를 getComputedStyle 로 다시 읽는다
    var rendered = getComputedStyle(cardRadius).borderTopLeftRadius;
    readout.textContent = 'Radius ' + rendered + ' · corner-shape ' + (supported ? 'applied' : 'not supported (fallback)');
  }

  function human() { if (isDemo) { wrap.classList.remove('is-demo'); isDemo = false; } }
  cardRadius.addEventListener('click', function () { human(); r = r === MIN_R ? MAX_R : MIN_R; apply(); });
  cardShape.addEventListener('click', function () { human(); r = r === MIN_R ? MAX_R : MIN_R; apply(); });

  var last = 0;
  function loop(ts) {
    if (!last) last = ts;
    if (isDemo && !reduce && ts - last >= STEP_MS) {
      last = ts;
      r = r === MIN_R ? MAX_R : MIN_R;
      apply();
    }
    requestAnimationFrame(loop);
  }
  apply();
  requestAnimationFrame(loop);
})();

// CornerShape — vanilla 판(run/376/demo/09-corner-shape/index.html) 의 React 포트.
// 클릭·자동 루프가 같은 반경 값을 두 카드에 동시에 넣고 getComputedStyle 로 실제 렌더 결과를
// 다시 읽는다. corner-shape 지원 여부는 CSS.supports 로 실측하고(추측 금지), 미지원 환경은
// @supports 블록이 자동으로 원호 폴백을 남긴다.
import { useEffect, useRef } from "react";
import styles from "./CornerShape.module.scss";

type Box<T> = { current: T };

const STEP_MS = 900;
const MIN_R = 10;
const MAX_R = 34;

export default function CornerShape() {
  const wrapRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const supportBadgeRef = useRef(null) as unknown as Box<HTMLSpanElement>;
  const cardRadiusRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const cardShapeRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const readoutRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const rafRef = useRef(0) as unknown as Box<number>;

  useEffect(() => {
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    const wrap = wrapRef.current;
    const supportBadge = supportBadgeRef.current;
    const cardRadius = cardRadiusRef.current;
    const cardShape = cardShapeRef.current;
    const readout = readoutRef.current;
    if (!wrap || !supportBadge || !cardRadius || !cardShape || !readout) return;

    const supported =
      typeof CSS !== "undefined" && !!CSS.supports && CSS.supports("corner-shape", "squircle");

    let isDemo = true;
    let r = MIN_R;

    supportBadge.textContent = supported ? "corner-shape 지원" : "미지원 환경 — 오른쪽은 원호로 자동 대체";
    supportBadge.classList.toggle(styles.fallback, !supported);

    function apply() {
      const px = Math.round(r) + "px";
      cardRadius!.style.borderRadius = px;
      cardShape!.style.borderRadius = px;
      const rendered = getComputedStyle(cardRadius!).borderTopLeftRadius;
      readout!.textContent = "반경 " + rendered + " · corner-shape " + (supported ? "적용됨" : "미지원(폴백)");
    }

    function human() { if (isDemo) { wrap!.classList.remove(styles.isDemo); isDemo = false; } }
    function onCardClick() { human(); r = r === MIN_R ? MAX_R : MIN_R; apply(); }
    cardRadius.addEventListener("click", onCardClick);
    cardShape.addEventListener("click", onCardClick);

    let last = 0;
    function loop(ts: number) {
      if (!last) last = ts;
      if (isDemo && !reduce && ts - last >= STEP_MS) {
        last = ts;
        r = r === MIN_R ? MAX_R : MIN_R;
        apply();
      }
      rafRef.current = requestAnimationFrame(loop);
    }
    apply();
    rafRef.current = requestAnimationFrame(loop);

    return () => {
      cardRadius!.removeEventListener("click", onCardClick);
      cardShape!.removeEventListener("click", onCardClick);
      cancelAnimationFrame(rafRef.current);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.wrap + " " + styles.isDemo} ref={wrapRef}>
        <span className={styles.supportBadge} ref={supportBadgeRef}>확인 중</span>
        <div className={styles.cards}>
          <div className={styles.cardCol}>
            <span className={styles.colLabel}>border-radius 기본 원호</span>
            <div className={styles.card + " " + styles.cardRadius} ref={cardRadiusRef}></div>
          </div>
          <div className={styles.cardCol}>
            <span className={styles.colLabel}>corner-shape 한 줄 추가</span>
            <div className={styles.card + " " + styles.cardShape} ref={cardShapeRef}></div>
          </div>
        </div>
        <div className={styles.readout} ref={readoutRef}>반경 —px</div>
      </div>
    </main>
  );
}