06Feature-support branch — a layout that checks support first, then switches its own rules

<main class="stage">
<div class="wrap is-demo" id="wrap">
  <div class="head">
    <span class="modeLabel" id="modeLabel">Live support check</span>
    <button class="rescanBtn" id="rescanBtn" type="button">Recheck</button>
  </div>
  <ul class="checkList" id="checkList"></ul>
  <div class="bar"><div class="barFill" id="barFill"></div></div>
  <button class="simToggle" id="simToggle" type="button" aria-pressed="false">Simulate fallback</button>
</div>
</main>

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

// 계산 겹은 index.html 의 scan() 에 있다 — CSS.supports() 로 실제 렌더 환경을 검사해 okCount/전체
// 비율을 구하고 그 비율을 막대 scaleX 에 그대로 반영한다(하드코딩 비율 아님). 여기는 목록 행의
// 등장 시차와 막대·아이콘 표기만 맡는다.
@include stage($stage-ink);

.wrap {
  width: 240px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
}

.head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.modeLabel {
  color: $subject-cream;
  font-size: 10px;
  font-weight: 700;
}

.rescanBtn {
  appearance: none;
  border: none;
  border-radius: $r-pill;
  background: $subject-blue;
  color: $subject-cream;
  padding: $sp-1 $sp-3;
  font-size: 10px;
  font-weight: 600;
  cursor: pointer;
  transition: transform $dur-instant $ease-out;

  &:active { transform: scale(.94); }
  &:focus-visible { outline: 2px solid $subject-blue-light; outline-offset: 2px; }
}

.checkList {
  width: 100%;
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: $sp-1;
}

.checkRow {
  display: flex;
  align-items: center;
  gap: $sp-2;
  padding: $sp-1 $sp-2;
  border-radius: $r-sm;
  background: rgba($subject-cream, .06);
  opacity: 0;
  transform: translateY(6px);
  transition: opacity $dur-base $ease-out, transform $dur-base $ease-out;
  transition-delay: calc(var(--i, 0) * 55ms);
}

.checkRow.is-revealed {
  opacity: 1;
  transform: translateY(0);
}

.checkRow.is-hidden {
  opacity: 0;
  transform: translateY(6px);
  transition-delay: 0ms;
}

.statusIcon {
  flex: 0 0 auto;
  width: 12px;
  height: 12px;
  border-radius: $r-pill;
  background: $subject-blue-light;
}

.checkRow.is-ok .statusIcon { background: $subject-mint; }
.checkRow.is-fallback .statusIcon { background: $error-soft; }

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

.bar {
  width: 100%;
  height: 6px;
  border-radius: $r-pill;
  background: rgba($subject-cream, .12);
  overflow: hidden;
}

.barFill {
  width: 100%;
  height: 100%;
  border-radius: $r-pill;
  background: $subject-mint;
  transform-origin: left center;
  transform: scaleX(0);
  transition: transform $dur-base $ease-out;
}

.simToggle {
  appearance: none;
  border: none;
  border-radius: $r-pill;
  background: rgba($subject-cream, .14);
  color: $subject-cream;
  padding: $sp-1 $sp-3;
  font-size: 10px;
  font-weight: 600;
  cursor: pointer;
  transition: transform $dur-instant $ease-out;

  &:active { transform: scale(.96); }
  &[aria-pressed="true"] { background: $subject-orange-deep; }
  &:focus-visible { outline: 2px solid $subject-blue-light; outline-offset: 2px; }
}

@media (max-width: 340px) {
  .wrap { width: 192px; gap: $sp-1; }
  .head { gap: $sp-1; }
  .featureName { font-size: 9px; }
  .checkList { gap: 0; }
  .checkRow { padding: 0 $sp-1; gap: $sp-1; }
}

@media (prefers-reduced-motion: reduce) {
  .checkRow { transition: none; }
  .barFill { transition: none; }
  .rescanBtn, .simToggle { 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: 240px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.modeLabel {
  color: #fff7e6;
  font-size: 10px;
  font-weight: 700;
}

.rescanBtn {
  appearance: none;
  border: none;
  border-radius: 999px;
  background: #2f6df6;
  color: #fff7e6;
  padding: 4px 12px;
  font-size: 10px;
  font-weight: 600;
  cursor: pointer;
  transition: transform 140ms ease-out;
}
.rescanBtn:active {
  transform: scale(0.94);
}
.rescanBtn:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

.checkList {
  width: 100%;
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.checkRow {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 4px 8px;
  border-radius: 8px;
  background: rgba(255, 247, 230, 0.06);
  opacity: 0;
  transform: translateY(6px);
  transition: opacity 300ms ease-out, transform 300ms ease-out;
  transition-delay: calc(var(--i, 0) * 55ms);
}

.checkRow.is-revealed {
  opacity: 1;
  transform: translateY(0);
}

.checkRow.is-hidden {
  opacity: 0;
  transform: translateY(6px);
  transition-delay: 0ms;
}

.statusIcon {
  flex: 0 0 auto;
  width: 12px;
  height: 12px;
  border-radius: 999px;
  background: #5b8cf8;
}

.checkRow.is-ok .statusIcon {
  background: #4cd4a6;
}

.checkRow.is-fallback .statusIcon {
  background: #ffe0d8;
}

.featureName {
  color: #fff7e6;
  font-size: 11px;
}

.bar {
  width: 100%;
  height: 6px;
  border-radius: 999px;
  background: rgba(255, 247, 230, 0.12);
  overflow: hidden;
}

.barFill {
  width: 100%;
  height: 100%;
  border-radius: 999px;
  background: #4cd4a6;
  transform-origin: left center;
  transform: scaleX(0);
  transition: transform 300ms ease-out;
}

.simToggle {
  appearance: none;
  border: none;
  border-radius: 999px;
  background: rgba(255, 247, 230, 0.14);
  color: #fff7e6;
  padding: 4px 12px;
  font-size: 10px;
  font-weight: 600;
  cursor: pointer;
  transition: transform 140ms ease-out;
}
.simToggle:active {
  transform: scale(0.96);
}
.simToggle[aria-pressed=true] {
  background: #c93000;
}
.simToggle:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

@media (max-width: 340px) {
  .wrap {
    width: 192px;
    gap: 4px;
  }
  .head {
    gap: 4px;
  }
  .featureName {
    font-size: 9px;
  }
  .checkList {
    gap: 0;
  }
  .checkRow {
    padding: 0 4px;
    gap: 4px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .checkRow {
    transition: none;
  }
  .barFill {
    transition: none;
  }
  .rescanBtn, .simToggle {
    transition: none;
  }
}

(function () {
  var STEP_MS = 620; // 자동 재검사/시뮬레이션 gap
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var wrap = document.getElementById('wrap');
  var checkList = document.getElementById('checkList');
  var barFill = document.getElementById('barFill');
  var rescanBtn = document.getElementById('rescanBtn');
  var simToggle = document.getElementById('simToggle');
  var modeLabel = document.getElementById('modeLabel');
  var isDemo = true;

  function human() { if (isDemo) { wrap.classList.remove('is-demo'); isDemo = false; } }

  // 실제 @supports 와 같은 판정 근거 — CSS.supports() 로 지금 렌더 환경을 그대로 검사한다
  var FEATURES = [
    { label: 'Flex gap', test: function () { return CSS.supports('gap', '1px'); } },
    { label: 'Aspect ratio', test: function () { return CSS.supports('aspect-ratio', '1 / 1'); } },
    { label: 'Backdrop blur', test: function () { return CSS.supports('backdrop-filter', 'blur(1px)'); } },
    { label: 'Parent selector', test: function () { return CSS.supports('selector(:has(a))'); } },
    { label: 'Container query', test: function () { return CSS.supports('container-type', 'inline-size'); } }
  ];

  var simOn = false;
  var rows = [];

  function build() {
    checkList.innerHTML = '';
    rows = FEATURES.map(function (f, i) {
      var li = document.createElement('li');
      li.className = 'checkRow is-hidden';
      li.style.setProperty('--i', String(i));
      var icon = document.createElement('span');
      icon.className = 'statusIcon';
      var name = document.createElement('span');
      name.className = 'featureName';
      name.textContent = f.label;
      li.appendChild(icon);
      li.appendChild(name);
      checkList.appendChild(li);
      return { el: li, icon: icon, ok: f.test() };
    });
  }
  build();

  function scan() {
    var okCount = 0;
    rows.forEach(function (row, i) {
      // 시뮬레이션판: 실제 결과 위에 강제로 미지원을 덧씌워 폴백 문구가 보이게 한다(감지 흉내가 아니라 표시 전용 오버라이드)
      var displayOk = simOn ? (row.ok && i % 2 === 0) : row.ok;
      row.el.classList.toggle('is-ok', displayOk);
      row.el.classList.toggle('is-fallback', !displayOk);
      row.el.classList.remove('is-hidden');
      row.el.classList.add('is-revealed');
      if (displayOk) okCount += 1;
    });
    var ratio = rows.length ? okCount / rows.length : 0;
    barFill.style.transform = 'scaleX(' + ratio + ')';
    modeLabel.textContent = simOn ? 'Simulated check' : 'Live support check';
  }

  rescanBtn.addEventListener('click', function () {
    human();
    rows.forEach(function (row) { row.el.classList.add('is-hidden'); row.el.classList.remove('is-revealed'); });
    requestAnimationFrame(function () { requestAnimationFrame(scan); });
  });

  function setSim(on) {
    simOn = on;
    simToggle.setAttribute('aria-pressed', String(on));
    scan();
  }
  simToggle.addEventListener('click', function () { human(); setSim(!simOn); });

  scan();

  var last = 0;
  var phase = 0;
  function loop(ts) {
    if (!last) last = ts;
    if (isDemo && !reduce && ts - last >= STEP_MS) {
      last = ts;
      phase = (phase + 1) % 3;
      if (phase === 0) {
        rows.forEach(function (row) { row.el.classList.add('is-hidden'); row.el.classList.remove('is-revealed'); });
      } else if (phase === 1) {
        scan();
      } else {
        setSim(!simOn);
      }
    }
    requestAnimationFrame(loop);
  }
  requestAnimationFrame(loop);
})();

// SupportsQuery — vanilla 판(run/375/demo/06-compat-supports-query/index.html) 의 React 포트.
// CSS.supports() 로 실제 렌더 환경을 검사해 항목별 지원/미지원을 표시하고, 통과 비율을 막대 scaleX 로 잰다.
import { useEffect, useRef } from "react";
import styles from "./SupportsQuery.module.scss";

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

const STEP_MS = 620; // 자동 재검사/시뮬레이션 간격

export default function SupportsQuery() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const checkListRef = useRef(null) as unknown as Box<HTMLUListElement>;
  const barFillRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const rescanBtnRef = useRef(null) as unknown as Box<HTMLButtonElement>;
  const simToggleRef = useRef(null) as unknown as Box<HTMLButtonElement>;
  const modeLabelRef = useRef(null) as unknown as Box<HTMLSpanElement>;
  const rafRef = useRef(0) as unknown as Box<number>;

  useEffect(() => {
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    const wrap = rootRef.current;
    const checkList = checkListRef.current;
    const barFill = barFillRef.current;
    const rescanBtn = rescanBtnRef.current;
    const simToggle = simToggleRef.current;
    const modeLabel = modeLabelRef.current;
    if (!wrap || !checkList || !barFill || !rescanBtn || !simToggle || !modeLabel) return;

    let isDemo = true;

    function human() { if (isDemo) { wrap!.classList.remove(styles.isDemo); isDemo = false; } }

    // 실제 @supports 와 같은 판정 근거 — CSS.supports() 로 지금 렌더 환경을 그대로 검사한다
    const FEATURES = [
      { label: "플렉스 gap", test: function () { return CSS.supports("gap", "1px"); } },
      { label: "가로세로비", test: function () { return CSS.supports("aspect-ratio", "1 / 1"); } },
      { label: "배경 흐림", test: function () { return CSS.supports("backdrop-filter", "blur(1px)"); } },
      { label: "부모 선택자", test: function () { return CSS.supports("selector(:has(a))"); } },
      { label: "컨테이너 쿼리", test: function () { return CSS.supports("container-type", "inline-size"); } }
    ];

    let simOn = false;
    let rows: { el: HTMLLIElement; icon: HTMLSpanElement; ok: boolean }[] = [];

    function build() {
      checkList!.innerHTML = "";
      rows = FEATURES.map(function (f, i) {
        const li = document.createElement("li");
        li.className = styles.checkRow + " " + styles.isHidden;
        li.style.setProperty("--i", String(i));
        const icon = document.createElement("span");
        icon.className = styles.statusIcon;
        const name = document.createElement("span");
        name.className = styles.featureName;
        name.textContent = f.label;
        li.appendChild(icon);
        li.appendChild(name);
        checkList!.appendChild(li);
        return { el: li, icon: icon, ok: f.test() };
      });
    }
    build();

    function hideAll() {
      rows.forEach(function (row) { row.el.classList.add(styles.isHidden); row.el.classList.remove(styles.isRevealed); });
    }

    function scan() {
      let okCount = 0;
      rows.forEach(function (row, i) {
        // 시뮬레이션판: 실제 결과 위에 강제로 미지원을 덧씌워 폴백 문구가 보이게 한다(감지 흉내가 아니라 표시 전용 오버라이드)
        const displayOk = simOn ? (row.ok && i % 2 === 0) : row.ok;
        row.el.classList.toggle(styles.isOk, displayOk);
        row.el.classList.toggle(styles.isFallback, !displayOk);
        row.el.classList.remove(styles.isHidden);
        row.el.classList.add(styles.isRevealed);
        if (displayOk) okCount += 1;
      });
      const ratio = rows.length ? okCount / rows.length : 0;
      barFill!.style.transform = "scaleX(" + ratio + ")";
      modeLabel!.textContent = simOn ? "폴백 흉내 검사" : "실제 지원 검사";
    }

    function onRescan() {
      human();
      hideAll();
      requestAnimationFrame(function () { requestAnimationFrame(scan); });
    }
    rescanBtn.addEventListener("click", onRescan);

    function setSim(on: boolean) {
      simOn = on;
      simToggle!.setAttribute("aria-pressed", String(on));
      scan();
    }
    function onSimClick() { human(); setSim(!simOn); }
    simToggle.addEventListener("click", onSimClick);

    scan();

    let last = 0;
    let phase = 0;
    function loop(ts: number) {
      if (!last) last = ts;
      if (isDemo && !reduce && ts - last >= STEP_MS) {
        last = ts;
        phase = (phase + 1) % 3;
        if (phase === 0) {
          hideAll();
        } else if (phase === 1) {
          scan();
        } else {
          setSim(!simOn);
        }
      }
      rafRef.current = requestAnimationFrame(loop);
    }
    rafRef.current = requestAnimationFrame(loop);

    return () => {
      rescanBtn!.removeEventListener("click", onRescan);
      simToggle!.removeEventListener("click", onSimClick);
      cancelAnimationFrame(rafRef.current);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.wrap + " " + styles.isDemo} ref={rootRef}>
        <div className={styles.head}>
          <span className={styles.modeLabel} ref={modeLabelRef}>실제 지원 검사</span>
          <button className={styles.rescanBtn} ref={rescanBtnRef} type="button">다시 검사</button>
        </div>
        <ul className={styles.checkList} ref={checkListRef}></ul>
        <div className={styles.bar}><div className={styles.barFill} ref={barFillRef}></div></div>
        <button className={styles.simToggle} ref={simToggleRef} type="button" aria-pressed="false">폴백 흉내내기</button>
      </div>
    </main>
  );
}