@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500&family=Noto+Sans+KR:wght@400;500;700;800&display=swap');

:root {
  --blue: #2563eb;
  --blue-light: #eff6ff;
  --blue-mid: #dbeafe;
  --orange: #ea580c;
  --orange-light: #fff7ed;
  --green: #059669;
  --green-light: #ecfdf5;
  --red: #dc2626;
  --red-light: #fef2f2;
  --yellow: #d97706;
  --yellow-light: #fffbeb;
  --bg: #f1f5f9;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --border: rgba(15, 23, 42, 0.09);
  --shadow-sm: 0 1px 4px rgba(15,23,42,0.07), 0 4px 16px rgba(15,23,42,0.05);
  --shadow: 0 2px 8px rgba(15,23,42,0.08), 0 8px 32px rgba(15,23,42,0.07);
  --radius: 16px;
  --radius-sm: 10px;
  --max: 1280px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Noto Sans KR", sans-serif;
  font-size: 17px;
  line-height: 1.85;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }

.shell {
  width: min(calc(100% - 40px), var(--max));
  margin: 0 auto;
}

/* ── 타이포그래피 ── */
h1, h2, h3, h4 {
  font-family: "Noto Sans KR", sans-serif;
  letter-spacing: -0.02em;
  word-break: keep-all;
  overflow-wrap: break-word;
}

.hero-title {
  margin: 12px 0 18px;
  font-size: clamp(2.4rem, 6vw, 4.5rem);
  font-weight: 800;
  line-height: 1.05;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.page-title {
  margin: 10px 0 14px;
  font-size: clamp(2rem, 5vw, 3.6rem);
  font-weight: 800;
  line-height: 1.05;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.section-title {
  margin: 6px 0 0;
  font-size: clamp(1.6rem, 3.5vw, 2.4rem);
  font-weight: 800;
  line-height: 1.1;
  word-break: keep-all;
}

.chapter-title {
  margin: 4px 0 0;
  font-size: 1.35rem;
  font-weight: 700;
  line-height: 1.25;
  word-break: keep-all;
}

.simulator-title {
  margin: 0 0 10px;
  font-size: 1.4rem;
  font-weight: 700;
}

/* ── 뱃지/eyebrow ── */
.eyebrow, .page-kicker, .chapter-meta, .roadmap-step small {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--blue);
}

/* ── 히어로 ── */
.hero {
  padding: 40px 0 24px;
}

.hero-grid, .page-hero {
  display: grid;
  grid-template-columns: 1.35fr 0.65fr;
  gap: 20px;
  align-items: stretch;
}

.hero-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 52px 52px 46px;
  position: relative;
  overflow: hidden;
}

.hero-card::before {
  content: "";
  position: absolute;
  top: -60px;
  right: -60px;
  width: 280px;
  height: 280px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(37,99,235,0.10), transparent 70%);
  pointer-events: none;
}

.hero-subtitle {
  font-size: 1.2rem;
  font-weight: 500;
  color: var(--blue);
  line-height: 1.4;
  word-break: keep-all;
  margin-bottom: 16px;
}

.hero-copy {
  font-size: 1rem;
  color: var(--muted);
  max-width: 800px;
  margin: 0 0 8px;
}

.mini-panel {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  padding: 32px 28px;
}

.hero-note h3 {
  margin: 0 0 14px;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
}

.hero-note p {
  margin: 0 0 12px;
  font-size: 0.95rem;
  color: var(--muted);
  line-height: 1.7;
}

.hero-note p:last-child { margin-bottom: 0; }

.hero-actions, .page-actions, .chapter-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

/* ── 버튼 ── */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 10px 22px;
  border-radius: 999px;
  border: 1.5px solid transparent;
  font-size: 15px;
  font-weight: 700;
  font-family: "Noto Sans KR", sans-serif;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s;
}

.button:hover { transform: translateY(-1px); box-shadow: 0 4px 16px rgba(37,99,235,0.18); }

.button.primary {
  background: var(--blue);
  color: #fff;
}

.button.secondary {
  background: transparent;
  border-color: var(--border);
  color: var(--text);
}

/* ── 섹션 ── */
.section {
  padding: 20px 0 16px;
}

.section-header {
  margin-bottom: 20px;
}

/* ── 로드맵/flow 그리드 ── */
.roadmap-grid {
  display: grid;
  gap: 14px;
}

.flow-grid {
  grid-template-columns: repeat(6, minmax(0, 1fr));
}

.roadmap-step {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  padding: 22px 20px;
}

.roadmap-step h3 {
  margin: 6px 0 8px;
  font-size: 1.1rem;
  font-weight: 700;
  line-height: 1.2;
  word-break: keep-all;
}

.roadmap-step p {
  margin: 0;
  font-size: 0.88rem;
  color: var(--muted);
  line-height: 1.55;
}

/* ── 챕터 카드 그리드 ── */
.card-grid { display: grid; gap: 16px; }

.chapter-list-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.chapter-card {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 26px 24px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.18s, transform 0.18s;
}

.chapter-card:hover {
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.chapter-card p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--muted);
  line-height: 1.6;
  flex: 1;
}

.chapter-actions { margin-top: auto; }

/* ── 페이지 레이아웃 ── */
.page-shell {
  padding: 28px 0 52px;
}

.page-hero {
  margin-bottom: 0;
}

.page-panel {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 40px 44px;
}

.page-question {
  margin: 0 0 6px;
  font-size: 1.15rem;
  color: var(--blue);
  font-weight: 500;
  line-height: 1.5;
  word-break: keep-all;
}

.goal-list {
  display: grid;
  gap: 10px;
  margin-top: 22px;
}

.goal-item {
  padding-left: 16px;
  border-left: 3px solid var(--blue);
  font-size: 0.95rem;
  color: var(--muted);
  line-height: 1.6;
}

.chapter-note {
  padding: 28px 24px;
  background: var(--blue-light);
  border-color: var(--blue-mid);
}

.chapter-note h3 {
  margin: 0 0 10px;
  font-size: 1rem;
  font-weight: 700;
  color: var(--blue);
}

.chapter-note p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--muted);
  line-height: 1.65;
}

/* ── 본문 콘텐츠 ── */
.page-body, .simulator-section {
  margin-top: 20px;
}

.content-stack {
  display: grid;
  gap: 16px;
}

.content-block {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  padding: 32px 36px;
  max-width: 900px;
}

.content-block h3 {
  margin: 0 0 16px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
  word-break: keep-all;
}

.content-block p {
  margin: 0 0 14px;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--text);
}

.content-block p:last-child { margin-bottom: 0; }

.equation {
  margin-top: 18px;
  padding: 16px 20px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--blue-mid);
  background: var(--blue-light);
  font-family: "IBM Plex Mono", monospace;
  font-size: 15px;
  overflow-x: auto;
  white-space: pre-wrap;
  color: var(--blue);
}

/* ── 새 인터랙티브 컴포넌트 ── */

/* callout */
.callout {
  display: flex;
  gap: 16px;
  padding: 22px 24px;
  border-radius: var(--radius-sm);
  border-left: 4px solid;
  max-width: 900px;
}

.callout-icon {
  font-size: 1.4rem;
  flex-shrink: 0;
  line-height: 1;
  margin-top: 2px;
}

.callout-body { flex: 1; }

.callout-title {
  font-weight: 700;
  font-size: 0.97rem;
  margin-bottom: 6px;
}

.callout-text {
  font-size: 0.95rem;
  line-height: 1.72;
  margin: 0;
}

.callout.insight {
  background: var(--blue-light);
  border-color: var(--blue);
}
.callout.insight .callout-title { color: var(--blue); }

.callout.analogy {
  background: var(--green-light);
  border-color: var(--green);
}
.callout.analogy .callout-title { color: var(--green); }

.callout.warning {
  background: var(--yellow-light);
  border-color: var(--yellow);
}
.callout.warning .callout-title { color: var(--yellow); }

/* highlight */
.highlight-block {
  border-left: 4px solid var(--orange);
  padding: 20px 24px;
  background: var(--orange-light);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  max-width: 900px;
}

.highlight-block p {
  margin: 0;
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.6;
  color: var(--orange);
  word-break: keep-all;
}

/* comparison */
.comparison-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  max-width: 900px;
}

.comparison-card {
  background: var(--card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 22px 20px;
}

.comparison-label {
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--blue);
  margin-bottom: 12px;
}

.comparison-card ul {
  margin: 0;
  padding-left: 18px;
}

.comparison-card li {
  font-size: 0.93rem;
  line-height: 1.7;
  color: var(--muted);
  margin-bottom: 6px;
}

.comparison-card li:last-child { margin-bottom: 0; }

/* steps */
.steps-block {
  max-width: 900px;
}

.steps-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 12px;
}

.steps-list {
  display: grid;
  gap: 0;
}

.step-item {
  border: 1px solid var(--border);
  border-bottom: none;
  background: var(--card);
  overflow: hidden;
}

.step-item:first-child { border-radius: var(--radius-sm) var(--radius-sm) 0 0; }
.step-item:last-child { border-radius: 0 0 var(--radius-sm) var(--radius-sm); border-bottom: 1px solid var(--border); }

.step-header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 20px;
  cursor: pointer;
  user-select: none;
  transition: background 0.15s;
}

.step-header:hover { background: var(--blue-light); }

.step-num {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--blue);
  color: #fff;
  font-size: 0.82rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.step-label {
  font-size: 0.97rem;
  font-weight: 600;
  flex: 1;
  word-break: keep-all;
}

.step-arrow {
  font-size: 0.8rem;
  color: var(--muted);
  transition: transform 0.2s;
}

.step-item.open .step-arrow { transform: rotate(90deg); }

.step-body {
  display: none;
  padding: 0 20px 18px 64px;
  font-size: 0.94rem;
  line-height: 1.75;
  color: var(--muted);
}

.step-item.open .step-body { display: block; }

/* quiz */
.quiz-block {
  background: var(--card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 24px 26px;
  max-width: 900px;
}

.quiz-label {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--blue);
  margin-bottom: 10px;
}

.quiz-question {
  font-size: 1.02rem;
  font-weight: 600;
  line-height: 1.55;
  margin-bottom: 18px;
  word-break: keep-all;
}

.quiz-options {
  display: grid;
  gap: 8px;
}

.quiz-option {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 12px 16px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  cursor: pointer;
  font-size: 0.93rem;
  line-height: 1.55;
  text-align: left;
  word-break: keep-all;
  transition: border-color 0.15s, background 0.15s;
  font-family: "Noto Sans KR", sans-serif;
  color: var(--text);
  width: 100%;
}

.quiz-option:hover { border-color: var(--blue); background: var(--blue-light); }

.quiz-option.correct {
  border-color: var(--green);
  background: var(--green-light);
  color: var(--green);
  font-weight: 600;
}

.quiz-option.wrong {
  border-color: var(--red);
  background: var(--red-light);
  color: var(--red);
}

.quiz-opt-letter {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 1px;
  transition: background 0.15s, color 0.15s;
}

.quiz-option.correct .quiz-opt-letter {
  background: var(--green);
  color: #fff;
}

.quiz-option.wrong .quiz-opt-letter {
  background: var(--red);
  color: #fff;
}

.quiz-feedback {
  margin-top: 14px;
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.92rem;
  line-height: 1.65;
  display: none;
}

.quiz-feedback.show { display: block; }
.quiz-feedback.correct-fb { background: var(--green-light); color: var(--green); border: 1px solid rgba(5,150,105,0.2); }
.quiz-feedback.wrong-fb { background: var(--red-light); color: #991b1b; border: 1px solid rgba(220,38,38,0.2); }

/* ── 시뮬레이터 ── */
.simulator-section { margin-top: 20px; }

.simulator-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 36px 40px;
}

.simulator-copy {
  margin: 0 0 20px;
  font-size: 0.95rem;
  color: var(--muted);
  line-height: 1.65;
}

.sim-panel { display: grid; gap: 14px; }

.sim-canvas {
  width: 100%;
  min-height: 320px;
  border-radius: var(--radius-sm);
  background: #fafbff;
  border: 1px solid var(--border);
  overflow: hidden;
}

.sim-canvas-secondary { min-height: 240px; }
.sim-canvas-tertiary { min-height: 220px; }

.controls {
  display: grid;
  gap: 10px;
  margin-top: 8px;
}

.control {
  display: grid;
  grid-template-columns: 200px 1fr 60px;
  gap: 12px;
  align-items: center;
  font-size: 0.9rem;
}

.control input, .control select {
  width: 100%;
  font-family: "Noto Sans KR", sans-serif;
}

input[type="range"] {
  accent-color: var(--blue);
}

.sim-output {
  padding: 14px 18px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--blue-light);
  font-size: 0.9rem;
  color: var(--text);
  line-height: 1.7;
}

.sim-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  font-size: 0.88rem;
  color: var(--muted);
}

.sim-legend span {
  display: inline-flex;
  align-items: center;
  gap: 7px;
}

.sim-legend i {
  width: 20px;
  height: 3px;
  border-radius: 2px;
  display: inline-block;
  flex-shrink: 0;
}

.sim-meta-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.sim-detail-box {
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  font-size: 0.88rem;
}

.sim-detail-box h4 {
  margin: 0 0 8px;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text);
}

.sim-detail-box ul {
  margin: 0;
  padding-left: 18px;
  color: var(--muted);
  line-height: 1.65;
}

.sim-formula {
  margin: 0;
  padding: 12px 16px;
  background: var(--blue-light);
  border: 1px solid var(--blue-mid);
  border-radius: var(--radius-sm);
  font-family: "IBM Plex Mono", monospace;
  font-size: 14px;
  color: var(--blue);
  overflow-x: auto;
}

/* ── 테이블 ── */
.table-like {
  width: 100%;
  border-collapse: collapse;
  margin-top: 16px;
  font-size: 0.92rem;
}

.table-like th, .table-like td {
  padding: 12px 10px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--border);
}

.table-like th {
  color: var(--blue);
  font-weight: 700;
  font-size: 0.85rem;
  letter-spacing: 0.03em;
}

/* ── 페이지 네비 ── */
.page-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-top: 28px;
}

.page-nav a {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  padding: 18px 22px;
  transition: box-shadow 0.15s, transform 0.15s;
}

.page-nav a:hover {
  box-shadow: var(--shadow);
  transform: translateY(-1px);
}

.page-nav small {
  display: block;
  font-size: 0.78rem;
  color: var(--muted);
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 4px;
}

.page-nav strong {
  display: block;
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.3;
  word-break: keep-all;
}

/* ── 반응형 ── */
@media (max-width: 1100px) {
  .flow-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .chapter-list-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 860px) {
  .hero-grid, .page-hero { grid-template-columns: 1fr; }
  .hero-card { padding: 36px 28px 32px; }
  .page-panel { padding: 28px 24px; }
  .hero-title, .page-title { white-space: normal; font-size: clamp(1.8rem, 7vw, 3rem); }
  .content-block { padding: 24px 20px; }
  .simulator-card { padding: 24px 20px; }
  .comparison-grid { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  body { font-size: 16px; }
  .shell { width: min(calc(100% - 24px), var(--max)); }
  .flow-grid, .chapter-list-grid, .page-nav, .sim-meta-grid { grid-template-columns: 1fr; }
  .control { grid-template-columns: 1fr; }
  .hero-title, .page-title { font-size: clamp(1.6rem, 8vw, 2.5rem); }
}

/* ── SVG 시뮬레이터 & 다이어그램 ── */
.svg-sim { width: 100%; overflow: visible; display: block; }
.svg-diagram { margin: 20px 0; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 18px; }
.svg-diagram svg { width: 100%; overflow: visible; }
.svg-diagram figcaption { font-size: .78rem; color: var(--muted); text-align: center; margin-top: 8px; }

.sim-controls { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-bottom: 10px; }
.sim-controls label { display: flex; align-items: center; gap: 6px; font-size: .82rem; color: var(--muted); }
.sim-controls input[type=range] { width: 100px; accent-color: var(--blue); }
.sim-stat { font-size: .8rem; font-family: 'IBM Plex Mono', monospace; color: var(--muted); padding: 6px 0 2px; }

/* SVG 수식 블록 */
.eqsvg { background: var(--blue-light); border-left: 4px solid var(--blue); border-radius: 0 8px 8px 0; padding: 14px 20px; margin: 18px 0; }
.eqsvg .et { font-size: .75rem; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; color: var(--blue); margin-bottom: 10px; }
.eqsvg svg { overflow: visible; display: block; }

/* 인라인 다이어그램 그리드 */
.diag-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin: 16px 0; }
.diag-grid .svg-diagram { margin: 0; }
@media (max-width: 600px) { .diag-grid { grid-template-columns: 1fr; } }

/* ── 리빌드 공통 컴포넌트 ── */

/* 이미지 갤러리 */
.img-gallery { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin: 18px 0; }
.img-card { border-radius: 10px; overflow: hidden; border: 1px solid var(--border); background: var(--card); box-shadow: var(--shadow-sm); }
.img-card img { width: 100%; height: 190px; object-fit: cover; display: block; }
.img-card figcaption { font-size: .71rem; color: var(--muted); padding: 7px 10px; line-height: 1.4; }
.img-card figcaption a { color: var(--blue); text-decoration: none; }
@media (max-width: 600px) { .img-gallery { grid-template-columns: 1fr; } }

/* 시뮬레이터 카드 */
.sim-card { background: var(--card); border: 1.5px solid var(--blue-mid); border-radius: var(--radius); padding: 22px 26px; margin: 22px 0; box-shadow: var(--shadow-sm); }
.sim-card .sim-eyebrow { font-size: 10px; font-weight: 700; letter-spacing: .13em; text-transform: uppercase; color: var(--blue); margin-bottom: 5px; }
.sim-card .sim-title { font-size: 1.08rem; font-weight: 700; margin: 0 0 6px; color: var(--text); }
.sim-card .sim-desc { font-size: .88rem; color: var(--muted); margin: 0 0 16px; line-height: 1.6; }
.sim-card canvas, .sim-card .sim-svg-wrap svg { border-radius: 8px; display: block; width: 100%; }
.sim-card .sim-controls { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-top: 12px; }
.sim-card .sim-controls label { font-size: .82rem; color: var(--muted); display: flex; align-items: center; gap: 6px; }
.sim-card .sim-controls input[type=range] { width: 110px; accent-color: var(--blue); }
.sim-card .sim-controls button { background: var(--blue); color: #fff; border: none; border-radius: 6px; padding: 5px 14px; font-size: .82rem; font-weight: 600; cursor: pointer; font-family: inherit; }
.sim-card .sim-controls button:hover { opacity: .85; }
.sim-card .sim-stat { font-size: .78rem; font-family: 'IBM Plex Mono', monospace; color: var(--muted); margin-top: 8px; }

/* 다이어그램 래퍼 (업그레이드) */
.diag-wrap { margin: 20px 0; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 20px; }
.diag-wrap figcaption { font-size: .78rem; color: var(--muted); text-align: center; margin-top: 10px; }

/* KaTeX 블록 수식 */
.katex-block { overflow-x: auto; padding: 14px 0; text-align: center; margin: 18px 0; }
.katex-wrap { background: var(--blue-light); border-left: 4px solid var(--blue); border-radius: 0 10px 10px 0; padding: 16px 20px; margin: 18px 0; }
.katex-wrap .kw-label { font-size: .73rem; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; color: var(--blue); margin-bottom: 10px; }
.katex-wrap .katex-display { margin: 0; }

/* 클릭형 수식 해설 카드 */
.formula-card {
  position: relative;
  cursor: pointer;
  transition: border-color .18s, box-shadow .18s, background .18s;
}

.formula-card:hover {
  border-color: var(--blue);
  box-shadow: var(--shadow-sm);
}

.formula-card:focus-visible {
  outline: 3px solid var(--blue-mid);
  outline-offset: 3px;
}

.formula-card::after {
  content: "수식 해설 열기";
  position: absolute;
  top: 10px;
  right: 12px;
  border: 1px solid var(--blue-mid);
  border-radius: 999px;
  background: #fff;
  color: var(--blue);
  font-size: .78rem;
  font-weight: 700;
  padding: 5px 10px;
  pointer-events: none;
}

.formula-card.open::after {
  content: "수식 해설 닫기";
  color: var(--green);
  border-color: rgba(5,150,105,.24);
}

.formula-help {
  display: none;
  margin-top: 14px;
  border-top: 1px solid var(--border);
  padding-top: 18px;
}

.formula-card.open .formula-help {
  display: block;
}

.formula-help-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
}

.formula-help-item {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px 17px;
}

.formula-help-item strong {
  display: block;
  color: var(--text);
  font-size: 1.02rem;
  margin-bottom: 8px;
}

.formula-help-item span {
  display: block;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.78;
}

.formula-specific {
  margin-top: 16px;
  border: 1.5px solid rgba(37, 99, 235, .2);
  border-radius: 10px;
  background: linear-gradient(180deg, #ffffff 0%, #f8fbff 100%);
  padding: 18px;
}

.formula-specific > strong {
  display: block;
  color: var(--blue);
  font-size: 1.08rem;
  margin-bottom: 13px;
}

.formula-specific-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.formula-specific-grid div {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 15px 16px;
}

.formula-specific-grid b {
  display: block;
  color: var(--text);
  font-size: 1rem;
  margin-bottom: 8px;
}

.formula-specific-grid span {
  display: block;
  color: #334155;
  font-size: 1.01rem;
  line-height: 1.82;
}

.formula-card code {
  white-space: pre-wrap;
}

.eqb.formula-card {
  padding: 20px 22px;
}

.eqb.formula-card code {
  color: #1e3a8a;
  font-size: 1.01rem;
  line-height: 1.95;
  overflow-x: auto;
}

.eqb.formula-card .et,
.katex-wrap.formula-card .kw-label {
  padding-right: 112px;
}

.formula-line-reader {
  margin-top: 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
  padding: 17px;
}

.formula-line-reader > strong {
  display: block;
  color: var(--text);
  font-size: 1.05rem;
  margin-bottom: 11px;
}

.formula-line-item {
  display: grid;
  grid-template-columns: minmax(220px, .75fr) 1fr 190px;
  gap: 12px;
  align-items: start;
  padding: 11px 0;
  border-top: 1px solid var(--border);
}

.formula-line-item:first-of-type {
  border-top: 0;
  padding-top: 0;
}

.formula-line-item code {
  display: block;
  color: #1e3a8a;
  background: var(--blue-light);
  border-radius: 7px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: .92rem;
  line-height: 1.62;
  padding: 10px 12px;
  overflow-x: auto;
}

.formula-line-item span {
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.78;
}

.katex-rendered-lines {
  display: grid;
  gap: 12px;
  margin: 12px 0 16px;
}

.katex-rendered-title {
  color: var(--green);
  font-size: .8rem;
  font-weight: 800;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.katex-rendered-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 230px;
  gap: 16px;
  align-items: center;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
}

.katex-render-target {
  overflow-x: auto;
  min-width: 0;
  padding: 4px 0;
}

.katex-render-target .katex-display {
  margin: 0;
  text-align: left;
}

.katex-render-target .katex {
  font-size: 1.08em;
}

.formula-mini-graph {
  display: block;
  width: 100%;
  max-width: 220px;
  height: 96px;
  background: #f8fafc;
  border: 1px solid var(--border);
  border-radius: 8px;
}

/* Boolean 갱신 규칙 카드 */
.boolean-rule-card {
  margin: 22px 0;
  border: 1.5px solid var(--blue-mid);
  border-left: 5px solid var(--blue);
  border-radius: 0 10px 10px 0;
  background: linear-gradient(180deg, #fff 0%, #f8fbff 100%);
  padding: 20px;
  box-shadow: var(--shadow-sm);
}

.boolean-rule-card .et {
  color: var(--blue);
  font-size: .86rem;
  font-weight: 800;
  letter-spacing: .08em;
  text-transform: uppercase;
  margin-bottom: 10px;
}

.boolean-rule-lead {
  color: var(--text);
  font-size: 1rem;
  line-height: 1.82;
  margin: 0 0 16px;
}

.boolean-node-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-bottom: 16px;
}

.boolean-node-grid div,
.boolean-rule-row,
.boolean-state-note {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 8px;
}

.boolean-node-grid div {
  padding: 13px 14px;
}

.boolean-node-grid strong {
  display: block;
  color: var(--blue);
  font-family: 'IBM Plex Mono', monospace;
  font-size: 1.15rem;
  margin-bottom: 5px;
}

.boolean-node-grid span {
  display: block;
  color: var(--muted);
  font-size: .88rem;
  line-height: 1.55;
}

.boolean-rule-grid {
  display: grid;
  gap: 10px;
}

.boolean-rule-row {
  display: grid;
  grid-template-columns: minmax(210px, .72fr) 1fr;
  gap: 14px;
  align-items: stretch;
  padding: 14px;
}

.boolean-rule-formula {
  display: flex;
  align-items: center;
  color: #1e3a8a;
  background: var(--blue-light);
  border-radius: 7px;
  padding: 13px 14px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 1.06rem;
  font-weight: 700;
  line-height: 1.45;
  overflow-x: auto;
}

.boolean-rule-meaning strong {
  display: block;
  color: var(--text);
  font-size: .83rem;
  margin-bottom: 5px;
}

.boolean-rule-meaning span {
  display: block;
  color: var(--muted);
  font-size: .95rem;
  line-height: 1.68;
}

.boolean-state-note {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 12px;
  align-items: start;
  margin-top: 14px;
  padding: 15px 16px;
}

.boolean-state-note strong {
  color: var(--green);
  font-size: .9rem;
  white-space: nowrap;
}

.boolean-state-note span {
  color: var(--text);
  font-size: .98rem;
  line-height: 1.72;
}

@media (max-width: 720px) {
  .formula-card::after {
    position: static;
    display: inline-block;
    margin-bottom: 10px;
  }
  .eqb.formula-card .et,
  .katex-wrap.formula-card .kw-label {
    padding-right: 0;
  }
  .formula-help-grid {
    grid-template-columns: 1fr;
  }
  .formula-specific-grid {
    grid-template-columns: 1fr;
  }
  .formula-line-item {
    grid-template-columns: 1fr;
  }
  .katex-rendered-row {
    grid-template-columns: 1fr;
  }
  .formula-mini-graph {
    max-width: none;
  }
}

@media (max-width: 860px) {
  .boolean-node-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .boolean-rule-row {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 560px) {
  .boolean-rule-card {
    padding: 16px;
  }
  .boolean-node-grid {
    grid-template-columns: 1fr;
  }
  .boolean-state-note {
    grid-template-columns: 1fr;
  }
}

/* 03장 노이즈 정량화 전용 카드 */
.noise-quant-grid {
  display: grid;
  gap: 14px;
  margin: 20px 0;
}

.noise-card {
  border: 1.5px solid var(--border);
  border-radius: 10px;
  background: var(--card);
  overflow: hidden;
}

.noise-card summary {
  list-style: none;
  cursor: pointer;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 12px;
  align-items: center;
  padding: 18px 20px;
}

.noise-card summary::-webkit-details-marker {
  display: none;
}

.noise-card summary strong {
  display: block;
  color: var(--text);
  font-size: 1.08rem;
  margin-bottom: 6px;
  line-height: 1.35;
}

.noise-card summary span {
  color: var(--muted);
  font-size: .96rem;
  line-height: 1.72;
}

.noise-card summary::after {
  content: "열기";
  border: 1px solid var(--blue-mid);
  border-radius: 999px;
  color: var(--blue);
  font-size: .72rem;
  font-weight: 700;
  padding: 5px 10px;
}

.noise-card[open] summary {
  background: var(--blue-light);
}

.noise-card[open] summary::after {
  content: "닫기";
  color: var(--green);
  border-color: rgba(5,150,105,.24);
}

.noise-card-body {
  padding: 0 20px 20px;
}

.noise-formula {
  background: #fff;
  border: 1px solid var(--border);
  border-left: 4px solid var(--blue);
  border-radius: 0 8px 8px 0;
  color: #1e3a8a;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 1.04rem;
  line-height: 1.82;
  padding: 16px 18px;
  overflow-x: auto;
}

.noise-meaning {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-top: 14px;
}

.noise-meaning div {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px 15px;
  color: var(--muted);
  font-size: .94rem;
  line-height: 1.72;
}

.noise-meaning strong {
  display: block;
  color: var(--text);
  font-size: .95rem;
  margin-bottom: 6px;
}

@media (max-width: 720px) {
  .noise-card summary {
    grid-template-columns: 1fr;
  }
  .noise-meaning {
    grid-template-columns: 1fr;
  }
}

/* ── 00A~09 보강 레이어 ── */
.chapter-enhancement-block h2 {
  font-size: 1.28rem;
  font-weight: 800;
  color: var(--text);
  margin: 0 0 16px;
  word-break: keep-all;
}

.chapter-enhancement-block p {
  font-size: .96rem;
  line-height: 1.9;
  color: var(--text);
  margin: 0 0 14px;
}

.chapter-long-explanation {
  margin: 18px 0;
  border: 1.5px solid var(--blue-mid);
  border-left: 5px solid var(--blue);
  border-radius: 0 10px 10px 0;
  background: #fff;
  padding: 18px 20px;
}

.chapter-long-explanation strong,
.chapter-data-source strong {
  display: block;
  color: var(--blue);
  font-size: .84rem;
  font-weight: 800;
  letter-spacing: .08em;
  text-transform: uppercase;
  margin-bottom: 8px;
}

.chapter-long-explanation p {
  margin: 0;
  color: var(--text);
  font-size: 1rem;
  line-height: 1.92;
  word-break: keep-all;
}

.chapter-data-source {
  margin: 16px 0 20px;
  border: 1px solid rgba(5,150,105,.22);
  border-radius: 8px;
  background: var(--green-light);
  padding: 14px 16px;
}

.chapter-data-source strong {
  color: var(--green);
}

.chapter-data-source span {
  display: block;
  color: var(--text);
  font-size: .94rem;
  line-height: 1.7;
}

.chapter-enhanced-gallery {
  margin-top: 20px;
}

.chapter-enhanced-image img {
  background: #f8fafc;
}

.chapter-enhanced-image figcaption strong {
  display: block;
  color: var(--text);
  font-size: .78rem;
  margin-bottom: 3px;
}

.chapter-reading-guide {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
  margin-top: 18px;
}

.chapter-reading-guide div {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 13px 14px;
}

.chapter-reading-guide strong {
  display: block;
  color: var(--blue);
  font-size: .78rem;
  letter-spacing: .08em;
  text-transform: uppercase;
  margin-bottom: 5px;
}

.chapter-reading-guide span {
  display: block;
  color: var(--muted);
  font-size: .82rem;
  line-height: 1.55;
}

.chapter-sim-suite {
  margin: 24px 0;
}

.chapter-mini-sim canvas {
  border: 1px solid var(--border);
  background: #f8fafc;
}

.chapter-mini-sim .sim-controls span[data-value] {
  min-width: 28px;
  color: var(--blue);
  font-family: "IBM Plex Mono", monospace;
  font-size: .78rem;
}

@media (max-width: 860px) {
  .chapter-reading-guide { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 560px) {
  .chapter-reading-guide { grid-template-columns: 1fr; }
  .chapter-mini-sim canvas { height: auto; }
}