01브라우저 기본값 리셋 — 요소마다 다른 여백과 목록 표시를 하나로 맞추는 시작점

<main class="stage">
<div class="wrap is-demo" id="wrap">
  <div class="head">
    <span class="stateLabel" id="stateLabel">리셋 전</span>
    <button class="toggleBtn" id="toggleBtn" type="button" aria-pressed="false">리셋 적용</button>
  </div>
  <div class="body">
    <div class="panel" id="panel">
      <h3 class="demoHeading">제목 영역</h3>
      <ul class="demoList">
        <li>항목 하나</li>
        <li>항목 둘</li>
        <li>항목 셋</li>
      </ul>
      <p class="demoPara">문단 여백은 브라우저마다 다릅니다. <a href="#" class="demoLink" id="demoLink">관련 링크</a></p>
    </div>
    <div class="ruler" id="ruler">
      <div class="rulerFill" id="rulerFill"></div>
    </div>
  </div>
  <div class="readout" id="readout">높이 —px · 지워진 기본값 —개</div>
</div>
</main>

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

// 계산 겹은 index.html 의 measure() 에 있다 — 패널의 실제 렌더 높이(getBoundingClientRect)를 매 프레임
// 다시 재서 룰러 막대의 scaleY 와 "높이 Npx" 문구에 그대로 반영한다. 여기는 리셋 전/후 두 규칙 집합과
// 룰러 모양만 맡는다.
@include stage($stage-ink);

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

.head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: $sp-2;
}

.stateLabel {
  color: $subject-cream;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .02em;
}

.toggleBtn {
  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: background $dur-instant $ease-out, transform $dur-instant $ease-out;

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

.body {
  display: flex;
  align-items: flex-start;
  gap: $sp-3;
}

// 패널은 일부러 우리 스타일을 씌우지 않는다 — .reset 이 없는 기본 상태가 곧 브라우저 기본값이다.
// font-size 를 11px 로 낮춰 h3·ul·p 의 em 기반 기본 여백을 실제 비율 그대로 작게 줄인다(값을 지어내지
// 않는다 — UA 스타일시트의 em 마진이 그대로 이 기준을 따라간다).
.panel {
  width: 220px;
  font-size: 11px;
  background: rgba($subject-cream, .08);
  border-radius: $r-sm;
  padding: $sp-2;
  transition: padding $dur-base $ease-out;
}

.demoHeading,
.demoPara,
.demoList {
  color: $subject-cream;
  transition: margin $dur-base $ease-out;
}

.demoList {
  transition: margin $dur-base $ease-out, padding $dur-base $ease-out;
}

.demoList li { color: $subject-cream; }

.demoLink {
  transition: color $dur-base $ease-out;
}

.panel.reset {
  .demoHeading, .demoPara, .demoList { margin: 0 0 $sp-2; }
  .demoList { padding: 0; list-style: none; }
  .demoList li { padding: $sp-1 0; }
}

.panel.reset.full .demoLink {
  color: $subject-blue-light;
  text-decoration: none;
}

.ruler {
  position: relative;
  width: 14px;
  height: 130px;
  border-radius: $r-xs;
  background: rgba($subject-cream, .1);
  align-self: flex-end;
  overflow: hidden;
}

.rulerFill {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 100%;
  transform-origin: bottom;
  transform: scaleY(0);
  background: $subject-blue-light;
  transition: transform $dur-base $ease-out;
}

.readout {
  color: $subject-cream;
  font-size: 11px;
  opacity: .82;
}

@media (max-width: 340px) {
  .wrap { width: 260px; gap: $sp-2; }
  .panel { width: 190px; padding: $sp-1; font-size: 9px; }
  .body { gap: $sp-2; }
  .ruler { height: 80px; }
  .demoList li:nth-child(3) { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  // reduce: 전환의 완만함만 지운다 — 상태 자체는 계속 바뀐다(모션이 아니라 값 전환이라 유지)
  .panel, .demoHeading, .demoPara, .demoList, .demoBtn, .rulerFill, .toggleBtn { 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;
}

.head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.stateLabel {
  color: #fff7e6;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.toggleBtn {
  appearance: none;
  border: none;
  border-radius: 999px;
  background: #2f6df6;
  color: #fff7e6;
  padding: 4px 12px;
  font-size: 10px;
  font-weight: 600;
  cursor: pointer;
  transition: background 140ms ease-out, transform 140ms ease-out;
}
.toggleBtn:hover {
  background: #5b8cf8;
}
.toggleBtn:active {
  transform: scale(0.96);
}
.toggleBtn[aria-pressed=true] {
  background: #c93000;
}
.toggleBtn:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

.body {
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

.panel {
  width: 220px;
  font-size: 11px;
  background: rgba(255, 247, 230, 0.08);
  border-radius: 8px;
  padding: 8px;
  transition: padding 300ms ease-out;
}

.demoHeading,
.demoPara,
.demoList {
  color: #fff7e6;
  transition: margin 300ms ease-out;
}

.demoList {
  transition: margin 300ms ease-out, padding 300ms ease-out;
}

.demoList li {
  color: #fff7e6;
}

.demoLink {
  transition: color 300ms ease-out;
}

.panel.reset .demoHeading, .panel.reset .demoPara, .panel.reset .demoList {
  margin: 0 0 8px;
}
.panel.reset .demoList {
  padding: 0;
  list-style: none;
}
.panel.reset .demoList li {
  padding: 4px 0;
}

.panel.reset.full .demoLink {
  color: #5b8cf8;
  text-decoration: none;
}

.ruler {
  position: relative;
  width: 14px;
  height: 130px;
  border-radius: 4px;
  background: rgba(255, 247, 230, 0.1);
  align-self: flex-end;
  overflow: hidden;
}

.rulerFill {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 100%;
  transform-origin: bottom;
  transform: scaleY(0);
  background: #5b8cf8;
  transition: transform 300ms ease-out;
}

.readout {
  color: #fff7e6;
  font-size: 11px;
  opacity: 0.82;
}

@media (max-width: 340px) {
  .wrap {
    width: 260px;
    gap: 8px;
  }
  .panel {
    width: 190px;
    padding: 4px;
    font-size: 9px;
  }
  .body {
    gap: 8px;
  }
  .ruler {
    height: 80px;
  }
  .demoList li:nth-child(3) {
    display: none;
  }
}
@media (prefers-reduced-motion: reduce) {
  .panel, .demoHeading, .demoPara, .demoList, .demoBtn, .rulerFill, .toggleBtn {
    transition: none;
  }
}

(function () {
  // 변형 상수 — minimal 은 목록·여백만, full 은 버튼 겉모습까지 지운다 (D 뒤 확정)
  var RESET_SCOPE = 'minimal';
  var STEP_MS = 320;
  // 지워지는 기본값 카테고리 — 실제로 화면에 세어 보여주는 목록이라 죽은 상수가 아니다
  var CLEARED_MINIMAL = ['heading-margin', 'paragraph-margin', 'list-style'];
  var CLEARED_FULL = CLEARED_MINIMAL.concat(['link-decoration']);
  var MAX_HEIGHT_PX = 130; // 룰러 눈금의 기준 최대 높이 — 이 값을 넘는 초과분은 눈금 밖으로 잘린다
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var wrap = document.getElementById('wrap');
  var panel = document.getElementById('panel');
  var toggleBtn = document.getElementById('toggleBtn');
  var stateLabel = document.getElementById('stateLabel');
  var readout = document.getElementById('readout');
  var rulerFill = document.getElementById('rulerFill');
  var isDemo = true;
  var on = false;

  function clearedList() { return RESET_SCOPE === 'full' ? CLEARED_FULL : CLEARED_MINIMAL; }

  function measure() {
    // 실측 — 패널의 실제 렌더 높이를 매 프레임 다시 잰다. 값을 미리 정해두지 않는다
    var h = panel.getBoundingClientRect().height;
    var ratio = Math.min(1, h / MAX_HEIGHT_PX);
    rulerFill.style.transform = 'scaleY(' + ratio.toFixed(3) + ')';
    readout.textContent = '높이 ' + Math.round(h) + 'px · 지워진 기본값 ' + (on ? clearedList().length : 0) + '개';
  }

  function apply(next) {
    on = next;
    panel.classList.toggle('reset', on);
    panel.classList.toggle('full', on && RESET_SCOPE === 'full');
    stateLabel.textContent = on ? '리셋 후' : '리셋 전';
    toggleBtn.setAttribute('aria-pressed', String(on));
  }

  function human() { if (isDemo) { wrap.classList.remove('is-demo'); isDemo = false; } }
  toggleBtn.addEventListener('click', function () { human(); apply(!on); });
  document.getElementById('demoLink').addEventListener('click', function (e) { human(); e.preventDefault(); });

  var last = 0;
  function loop(ts) {
    if (!last) last = ts;
    if (isDemo && !reduce && ts - last >= STEP_MS) { last = ts; apply(!on); }
    measure();
    requestAnimationFrame(loop);
  }
  requestAnimationFrame(loop);
})();

// Reset — vanilla 판(run/376/demo/01-reset/index.html) 의 React 포트.
// 패널에 .reset 클래스를 토글해 브라우저 기본값(h3·ul·p 여백)이 지워지는 전후를 보여주고,
// 룰러 막대는 실제 렌더 높이(getBoundingClientRect)를 매 프레임 다시 재 채운다.
import { useEffect, useRef } from "react";
import styles from "./Reset.module.scss";

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

const RESET_SCOPE: "minimal" | "full" = "minimal";
const STEP_MS = 320;
const CLEARED_MINIMAL = ["heading-margin", "paragraph-margin", "list-style"];
const CLEARED_FULL = CLEARED_MINIMAL.concat(["link-decoration"]);
const MAX_HEIGHT_PX = 130;

export default function Reset() {
  const wrapRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const panelRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const toggleBtnRef = useRef(null) as unknown as Box<HTMLButtonElement>;
  const stateLabelRef = useRef(null) as unknown as Box<HTMLSpanElement>;
  const readoutRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const rulerFillRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const demoLinkRef = useRef(null) as unknown as Box<HTMLAnchorElement>;
  const rafRef = useRef(0) as unknown as Box<number>;

  useEffect(() => {
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    const wrap = wrapRef.current;
    const panel = panelRef.current;
    const toggleBtn = toggleBtnRef.current;
    const stateLabel = stateLabelRef.current;
    const readout = readoutRef.current;
    const rulerFill = rulerFillRef.current;
    const demoLink = demoLinkRef.current;
    if (!wrap || !panel || !toggleBtn || !stateLabel || !readout || !rulerFill || !demoLink) return;

    let isDemo = true;
    let on = false;

    function clearedList() {
      return RESET_SCOPE === "full" ? CLEARED_FULL : CLEARED_MINIMAL;
    }

    function measure() {
      const h = panel!.getBoundingClientRect().height;
      const ratio = Math.min(1, h / MAX_HEIGHT_PX);
      rulerFill!.style.transform = "scaleY(" + ratio.toFixed(3) + ")";
      readout!.textContent = "높이 " + Math.round(h) + "px · 지워진 기본값 " + (on ? clearedList().length : 0) + "개";
    }

    function apply(next: boolean) {
      on = next;
      panel!.classList.toggle(styles.reset, on);
      panel!.classList.toggle(styles.full, on && RESET_SCOPE === "full");
      stateLabel!.textContent = on ? "리셋 후" : "리셋 전";
      toggleBtn!.setAttribute("aria-pressed", String(on));
    }

    function human() { if (isDemo) { wrap!.classList.remove(styles.isDemo); isDemo = false; } }
    function onToggleClick() { human(); apply(!on); }
    function onLinkClick(e: MouseEvent) { human(); e.preventDefault(); }
    toggleBtn.addEventListener("click", onToggleClick);
    demoLink.addEventListener("click", onLinkClick);

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

    return () => {
      toggleBtn!.removeEventListener("click", onToggleClick);
      demoLink!.removeEventListener("click", onLinkClick);
      cancelAnimationFrame(rafRef.current);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.wrap + " " + styles.isDemo} ref={wrapRef}>
        <div className={styles.head}>
          <span className={styles.stateLabel} ref={stateLabelRef}>리셋 전</span>
          <button className={styles.toggleBtn} ref={toggleBtnRef} type="button" aria-pressed="false">리셋 적용</button>
        </div>
        <div className={styles.body}>
          <div className={styles.panel} ref={panelRef}>
            <h3 className={styles.demoHeading}>제목 영역</h3>
            <ul className={styles.demoList}>
              <li>항목 하나</li>
              <li>항목 둘</li>
              <li>항목 셋</li>
            </ul>
            <p className={styles.demoPara}>문단 여백은 브라우저마다 다릅니다. <a href="#" className={styles.demoLink} ref={demoLinkRef}>관련 링크</a></p>
          </div>
          <div className={styles.ruler}>
            <div className={styles.rulerFill} ref={rulerFillRef}></div>
          </div>
        </div>
        <div className={styles.readout} ref={readoutRef}>높이 —px · 지워진 기본값 —개</div>
      </div>
    </main>
  );
}