/* ═══════════════════════════════════════════════════════════════
   Business Models & Frameworks Notes — styles.css
   Design system: Modern SaaS Adaptive Theme (Dark default)
   ═══════════════════════════════════════════════════════════════ */

/* ── Reset & Base ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ── Color Tokens — Dark (Default) ── */
:root {
  --bg:           #09090b;
  --surface:      #111113;
  --card:         #18181b;

  --border:       #27272a;
  --border-light: #3f3f46;

  --text:         #fafafa;
  --muted:        #a1a1aa;
  --dim:          #52525b;

  --accent:       #6366f1;
  --accent2:      #818cf8;
  --accent3:      #a5b4fc;

  --green:        #22c55e;
  --amber:        #f59e0b;
  --coral:        #f97316;
  --pink:         #ec4899;
  --teal:         #14b8a6;

  --shadow:       0 1px 3px rgba(0,0,0,0.4);
  --shadow-md:    0 4px 12px rgba(0,0,0,0.5);

  --radius-sm:    4px;
  --radius-md:    8px;
  --radius-lg:    12px;

  --topbar-height: 40px;
}

/* ── Light Mode ── */
.light, [data-theme="light"] {
  --bg:           #fafaf9;
  --surface:      #f4f4f5;
  --card:         #ffffff;
  --border:       #e4e4e7;
  --border-light: #d4d4d8;
  --text:         #09090b;
  --muted:        #52525b;
  --dim:          #a1a1aa;
  --shadow:       0 1px 3px rgba(0,0,0,0.06);
  --shadow-md:    0 4px 12px rgba(0,0,0,0.08);

  --green-text:   #15803d;
  --amber-text:   #b45309;
  --coral-text:   #c2410c;
  --pink-text:    #be185d;
  --teal-text:    #0f766e;
}

/* ── Body & Typography ── */
html, body {
  height: 100%;
  font-family: 'Segoe UI', system-ui, sans-serif;
  font-size: 15px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  transition: background-color 0.2s ease, color 0.2s ease;
}

/* ── Topbar ── */
.site-topbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--topbar-height);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  z-index: 100;
}

.topbar-inner {
  display: flex;
  align-items: center;
  height: 100%;
  padding: 0 16px;
  gap: 12px;
}

.topbar-brand {
  display: flex;
  align-items: center;
  gap: 6px;
  text-decoration: none;
  color: var(--text);
  flex-shrink: 0;
}

.topbar-logo-mark {
  font-size: 12px;
  font-weight: 700;
  background: var(--accent);
  color: #fff;
  padding: 2px 5px;
  border-radius: 3px;
  letter-spacing: .03em;
}

.topbar-logo-text {
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
}

.topbar-breadcrumb {
  display: flex;
  align-items: center;
  gap: 4px;
  flex: 1;
  overflow: hidden;
}

.topbar-bc-link {
  font-size: 12px;
  color: var(--muted);
  text-decoration: none;
  white-space: nowrap;
}
.topbar-bc-link:hover { color: var(--text); }

.topbar-bc-sep { font-size: 11px; color: var(--dim); }

.topbar-bc-current {
  font-size: 12px;
  color: var(--text);
  font-weight: 500;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.topbar-theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 3px 8px;
  cursor: pointer;
  color: var(--muted);
  font-size: 13px;
  flex-shrink: 0;
  transition: border-color .15s, color .15s;
}
.topbar-theme-toggle:hover { color: var(--text); border-color: var(--border-light); }

.topbar-request {
  font-size: 11px;
  font-weight: 600;
  color: var(--accent2);
  text-decoration: none;
  border: 1px solid var(--accent);
  border-radius: var(--radius-sm);
  padding: 3px 8px;
  flex-shrink: 0;
  transition: background .15s, color .15s;
}
.topbar-request:hover { background: var(--accent); color: #fff; }

/* Icon swap for theme toggle */
.icon-light { display: none; }
.icon-dark  { display: inline; }
.light .icon-dark  { display: none; }
.light .icon-light { display: inline; }

/* ── App Layout ── */
.app-layout {
  display: flex;
  height: calc(100vh - var(--topbar-height));
  margin-top: var(--topbar-height);
}

/* ── Sidebar ── */
.sidebar {
  width: 240px;
  min-width: 240px;
  background: var(--surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  height: calc(100vh - var(--topbar-height));
  position: sticky;
  top: var(--topbar-height);
}

.sidebar-label {
  padding: 12px 14px 8px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--dim);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

#toc-nav {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
}

#toc-nav::-webkit-scrollbar { width: 3px; }
#toc-nav::-webkit-scrollbar-thumb { background: var(--border-light); border-radius: 2px; }
#toc-nav::-webkit-scrollbar-track { background: transparent; }

/* TOC Items */
a.toc-header, a.toc-sub {
  text-decoration: none;
  color: inherit;
  display: flex;
}

.toc-item {
  border-bottom: 1px solid var(--border);
}

.toc-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 14px;
  font-size: 13px;
  font-weight: 500;
  color: var(--muted);
  cursor: pointer;
  transition: color .15s, background .15s;
  text-decoration: none;
}

.toc-header:hover { color: var(--text); background: rgba(99,102,241,.05); }
.light .toc-header:hover { background: rgba(0,0,0,.03); }

.toc-header.active {
  color: var(--accent);
  background: rgba(99,102,241,.08);
  border-left: 2px solid var(--accent);
  padding-left: 12px;
}

.toc-icon { font-size: 14px; flex-shrink: 0; }
.toc-label { flex: 1; }

.toc-chevron {
  font-size: 9px;
  color: var(--dim);
  transition: transform .2s ease;
  flex-shrink: 0;
}

.toc-item.open .toc-chevron { transform: rotate(90deg); }

.toc-subs {
  display: none;
  padding: 4px 0;
  background: var(--bg);
  border-top: 1px solid var(--border);
}

.toc-item.open .toc-subs { display: block; }

.toc-sub {
  display: block;
  padding: 6px 14px 6px 36px;
  font-size: 12px;
  color: var(--dim);
  text-decoration: none;
  transition: color .15s, background .15s;
}

.toc-sub:hover { color: var(--text); background: rgba(99,102,241,.04); }
.light .toc-sub:hover { background: rgba(0,0,0,.02); }

.toc-sub.active {
  color: var(--accent2);
  font-weight: 500;
  background: rgba(99,102,241,.06);
}

/* ── Sidebar Footer / Progress ── */
.sidebar-footer {
  padding: 10px 14px;
  border-top: 1px solid var(--border);
  flex-shrink: 0;
}

.progress-meta {
  display: flex;
  justify-content: space-between;
  font-size: 11px;
  color: var(--dim);
  margin-bottom: 5px;
}

.progress-bar {
  height: 2px;
  background: var(--border);
  border-radius: 2px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 2px;
  width: 0%;
  transition: width .4s ease;
}

/* ── Main Content ── */
.main-content {
  flex: 1;
  overflow-y: auto;
  height: calc(100vh - var(--topbar-height));
}

.main-header {
  padding: 16px 48px 0;
  max-width: 960px;
  margin: 0 auto;
}

.breadcrumb {
  font-size: 12px;
  color: var(--dim);
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 4px;
}

.breadcrumb .bc-active { color: var(--muted); }

.content-wrap {
  max-width: 960px;
  margin: 0 auto;
  padding: 24px 48px 60px;
}

#content-area { min-height: 200px; }

/* ── Content Container ── */
.content-container {
  padding-bottom: 16px;
}

/* ── Typography ── */
h1, h2 {
  font-size: 26px;
  font-weight: 700;
  line-height: 1.25;
  color: var(--text);
  margin-bottom: 8px;
}

h3 {
  font-size: 19px;
  font-weight: 600;
  color: var(--text);
  margin: 28px 0 10px;
}

h4 {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  margin: 20px 0 8px;
}

.body-text {
  font-size: 15px;
  line-height: 1.75;
  color: var(--muted);
  margin-bottom: 16px;
}

p {
  font-size: 15px;
  line-height: 1.75;
  color: var(--muted);
  margin-bottom: 16px;
}

strong { color: var(--text); }
em { color: var(--muted); }

ul, ol {
  padding-left: 20px;
  margin-bottom: 16px;
  color: var(--muted);
}

li {
  margin-bottom: 6px;
  line-height: 1.65;
  font-size: 15px;
}

/* ── Difficulty Badge ── */
.difficulty-badge {
  display: inline-block;
  font-size: 11px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 20px;
  margin-bottom: 20px;
  letter-spacing: .03em;
}

.difficulty-badge.beginner    { background: rgba(34,197,94,.12);  color: var(--green); border: 1px solid rgba(34,197,94,.25); }
.difficulty-badge.intermediate{ background: rgba(245,158,11,.12); color: var(--amber); border: 1px solid rgba(245,158,11,.25); }
.difficulty-badge.advanced    { background: rgba(249,115,22,.12); color: var(--coral); border: 1px solid rgba(249,115,22,.25); }
.difficulty-badge.expert      { background: rgba(239,68,68,.12);  color: #ef4444;      border: 1px solid rgba(239,68,68,.25); }

/* ── Stat Grid ── */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin: 20px 0 28px;
}

@media (max-width: 767px) {
  .stat-grid { grid-template-columns: repeat(2, 1fr); }
}

.stat-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  border-top: 3px solid var(--accent);
}

.stat-value {
  font-size: 22px;
  font-weight: 700;
  color: var(--sv-color, var(--accent2));
  line-height: 1.2;
  margin-bottom: 4px;
}

.stat-label {
  font-size: 11px;
  color: var(--dim);
  line-height: 1.4;
}

/* ── Tables ── */
.table-wrapper {
  overflow-x: auto;
  margin: 20px 0;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

th {
  background: var(--surface);
  color: var(--text);
  font-weight: 600;
  padding: 10px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: .04em;
}

td {
  padding: 10px 14px;
  color: var(--muted);
  border-bottom: 1px solid var(--border);
  vertical-align: top;
  line-height: 1.55;
}

tr:last-child td { border-bottom: none; }
tr:hover td { background: rgba(255,255,255,.02); }
.light tr:hover td { background: rgba(0,0,0,.02); }

/* ── Callout Boxes ── */
.callout {
  border-radius: var(--radius-md);
  padding: 14px 18px;
  margin: 20px 0;
  border-left: 3px solid;
  font-size: 14px;
  line-height: 1.65;
}

.callout-green  { background: rgba(34,197,94,.07);  border-color: var(--green);  color: var(--muted); }
.callout-amber  { background: rgba(245,158,11,.07); border-color: var(--amber);  color: var(--muted); }
.callout-coral  { background: rgba(249,115,22,.07); border-color: var(--coral);  color: var(--muted); }
.callout-teal   { background: rgba(20,184,166,.07); border-color: var(--teal);   color: var(--muted); }
.callout-accent { background: rgba(99,102,241,.07); border-color: var(--accent); color: var(--muted); }

.callout strong { color: var(--text); }

.callout-title {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  margin-bottom: 6px;
}

.callout-green  .callout-title { color: var(--green); }
.callout-amber  .callout-title { color: var(--amber); }
.callout-coral  .callout-title { color: var(--coral); }
.callout-teal   .callout-title { color: var(--teal);  }
.callout-accent .callout-title { color: var(--accent); }

/* ── Framework / Formula Blocks ── */
.formula-block {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-md);
  padding: 16px 20px;
  margin: 20px 0;
  font-family: 'Segoe UI', system-ui, sans-serif;
  font-size: 15px;
}

.formula-block .formula-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--dim);
  margin-bottom: 8px;
}

.formula-block .formula-body {
  color: var(--text);
  font-weight: 600;
}

/* ── Tab System ── */
.tab-group { margin: 24px 0; }

.tab-buttons {
  display: flex;
  gap: 2px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 0;
}

.tab-btn {
  padding: 8px 16px;
  font-size: 13px;
  font-weight: 500;
  color: var(--dim);
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  cursor: pointer;
  transition: color .15s, border-color .15s;
  margin-bottom: -1px;
}

.tab-btn:hover { color: var(--text); }
.tab-btn.active { color: var(--accent); border-bottom-color: var(--accent); }

.tab-panel {
  display: none;
  padding: 20px 0;
}
.tab-panel.active { display: block; }

/* ── Expandable Blocks ── */
.expandable {
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  margin: 12px 0;
  overflow: hidden;
}

.expand-trigger {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 16px;
  background: var(--surface);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  color: var(--text);
  border: none;
  width: 100%;
  text-align: left;
}

.expand-trigger:hover { background: rgba(99,102,241,.05); }
.expand-icon { font-size: 11px; color: var(--dim); transition: transform .2s; }
.expandable.open .expand-icon { transform: rotate(90deg); }

.expand-body {
  display: none;
  padding: 16px;
  font-size: 14px;
  color: var(--muted);
  line-height: 1.65;
  border-top: 1px solid var(--border);
}
.expandable.open .expand-body { display: block; }

/* ── Framework Display ── */
.framework-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin: 20px 0;
}

@media (max-width: 600px) {
  .framework-grid { grid-template-columns: 1fr; }
}

.framework-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 14px 16px;
}

.framework-card-title {
  font-size: 13px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 6px;
}

.framework-card p {
  font-size: 13px;
  color: var(--muted);
  margin: 0;
}

/* ── Scenario / Worked Example Block ── */
.worked-example {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin: 24px 0;
}

.worked-example-label {
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--accent2);
  margin-bottom: 10px;
}

.worked-example h4 {
  margin-top: 0;
  margin-bottom: 12px;
  color: var(--text);
}

/* ── Code Blocks ── */
.code-block {
  background: #18181b;
  border: 1px solid #27272a;
  border-radius: var(--radius-md);
  margin: 16px 0;
  overflow: hidden;
}

.light .code-block              { background: #18181b; border-color: #27272a; }
.light .code-block .code-header { background: #111113; border-color: #27272a; }
.light .code-block code         { color: #fafafa; }

.code-header {
  background: #111113;
  padding: 7px 14px;
  font-size: 11px;
  color: #71717a;
  border-bottom: 1px solid #27272a;
  text-transform: uppercase;
  letter-spacing: .05em;
}

.code-block code {
  display: block;
  padding: 16px;
  font-family: 'Cascadia Code', 'Fira Code', Consolas, monospace;
  font-size: 13px;
  color: #fafafa;
  overflow-x: auto;
  white-space: pre;
  line-height: 1.65;
}

/* ── Section Divider ── */
.section-divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 32px 0;
}

/* ── Country Tab Pattern ── */
.country-tabs { margin: 24px 0; }
.country-tab-buttons { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 14px; }

.country-tab-btn {
  padding: 5px 12px;
  font-size: 12px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: var(--surface);
  color: var(--muted);
  cursor: pointer;
  transition: all .15s;
}
.country-tab-btn:hover { color: var(--text); border-color: var(--teal); }
.country-tab-btn.active { color: var(--teal); border-color: var(--teal); background: rgba(20,184,166,.08); font-weight: 500; }

.country-tab-panel { display: none; }
.country-tab-panel.active { display: block; }

/* ── Quiz & Knowledge Check ── */
.topic-quick-check { margin-top: 40px; padding-top: 32px; border-top: 1px solid var(--border); }
.topic-quick-check h3 { margin-bottom: 4px; }

.mini-quiz-section { margin-top: 40px; padding-top: 32px; border-top: 1px solid var(--border); }
.mini-quiz-section h3 { margin-bottom: 4px; }
.mini-quiz-block { margin-bottom: 32px; }
.mini-quiz-block h4, .knowledge-check-block h4 { font-size: 13px; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); margin-bottom: 16px; }

.quiz-question {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px 18px;
  margin-bottom: 12px;
}

.quiz-q {
  font-size: 14px;
  font-weight: 500;
  color: var(--text);
  margin-bottom: 12px;
  line-height: 1.55;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 10px;
}

.quiz-opt {
  padding: 8px 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--muted);
  font-size: 13px;
  text-align: left;
  cursor: pointer;
  transition: border-color .15s, color .15s, background .15s;
}
.quiz-opt:hover { border-color: var(--accent); color: var(--text); }

.quiz-question.answered .quiz-opt { cursor: default; pointer-events: none; }
.quiz-opt.correct { border-color: var(--green); color: var(--green); background: rgba(34,197,94,.07); }
.quiz-opt.wrong   { border-color: var(--coral); color: var(--coral); background: rgba(249,115,22,.07); }

.quiz-explain {
  display: none;
  font-size: 13px;
  color: var(--muted);
  background: var(--surface);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
  border: 1px solid var(--border);
  line-height: 1.6;
}

.quiz-question.answered .quiz-explain { display: block; }

/* Knowledge Check */
.kc-item { border: 1px solid var(--border); border-radius: var(--radius-md); margin-bottom: 10px; overflow: hidden; }
.kc-question { width: 100%; display: flex; justify-content: space-between; align-items: flex-start; padding: 12px 16px; background: var(--surface); border: none; cursor: pointer; text-align: left; gap: 12px; }
.kc-question:hover { background: rgba(99,102,241,.05); }
.light .kc-question:hover { background: rgba(99,102,241,.04); }
.kc-q-text { font-size: 14px; color: var(--text); font-weight: 500; line-height: 1.5; }
.kc-toggle { font-size: 11px; color: var(--muted); flex-shrink: 0; margin-top: 3px; transition: transform .2s ease; }
.kc-item.open .kc-toggle { transform: rotate(180deg); }
.kc-answer { display: none; padding: 14px 16px; border-top: 1px solid var(--border); background: var(--bg); font-size: 14px; line-height: 1.65; color: var(--text); }
.kc-item.open .kc-answer { display: block; }
.kc-answer p { margin-bottom: 10px; color: var(--muted); }
.kc-answer p:last-child { margin-bottom: 0; }
.kc-section { padding-bottom: 16px; }

/* ── Subtopic Navigation ── */
.subtopic-nav {
  margin-top: 36px;
  padding: 14px 0 10px;
  border-top: 1px solid var(--border);
}

.subtopic-nav-label {
  display: block;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--dim);
  margin-bottom: 8px;
}

.subtopic-nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.subtopic-nav-link {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 4px;
  font-size: 12px;
  color: var(--muted);
  background: var(--surface);
  border: 1px solid var(--border);
  text-decoration: none;
  transition: color .15s, border-color .15s;
  cursor: pointer;
}

.subtopic-nav-link:hover { color: var(--text); border-color: var(--accent); }

.subtopic-nav-link.active {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(99,102,241,.07);
  font-weight: 500;
  pointer-events: none;
}

/* ── Prev / Next Footer ── */
.topic-nav-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  flex-wrap: wrap;
  gap: 8px;
}

.topic-nav-prev, .topic-nav-next {
  font-size: 13px;
  color: var(--accent2);
  text-decoration: none;
  transition: color .15s;
}
.topic-nav-prev:hover, .topic-nav-next:hover { color: var(--accent); }
.topic-nav-next { margin-left: auto; }

/* ── Cheatsheet ── */
.cheatsheet-section {
  margin-bottom: 36px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.cheatsheet-section h3 {
  margin: 0;
  padding: 12px 18px;
  background: var(--surface);
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--muted);
  border-bottom: 1px solid var(--border);
}

.cs-grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  padding: 14px;
}
.cs-grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  padding: 14px;
}

@media (max-width: 680px) {
  .cs-grid-2, .cs-grid-3 { grid-template-columns: 1fr; }
}

.cs-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 12px 14px;
}

.cs-card-title {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .05em;
  margin-bottom: 8px;
  color: var(--muted);
}

.cs-items {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.cs-items span {
  font-size: 12px;
  color: var(--muted);
  line-height: 1.45;
}

.cs-formula-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-top: 3px solid var(--accent);
  border-radius: var(--radius-md);
  padding: 12px 14px;
}

.cs-f-name {
  font-size: 12px;
  font-weight: 700;
  color: var(--accent2);
  margin-bottom: 6px;
}

.cs-f-formula {
  font-size: 13px;
  font-style: italic;
  color: var(--text);
  margin-bottom: 4px;
}

.cs-f-note {
  font-size: 11px;
  color: var(--dim);
  margin-top: 4px;
}

.cheatsheet-table-wrap {
  padding: 0 14px 14px;
}

/* ── Mobile ── */
@media (max-width: 767px) {
  .sidebar {
    position: fixed;
    left: 0;
    top: var(--topbar-height);
    height: calc(100vh - var(--topbar-height));
    z-index: 90;
    transform: translateX(-100%);
    transition: transform .25s ease;
    width: 280px;
  }
  .sidebar.open { transform: translateX(0); }

  #sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,.5);
    z-index: 80;
    top: var(--topbar-height);
  }
  #sidebar-overlay.visible { display: block; }

  .mobile-nav-toggle {
    position: fixed;
    bottom: 20px;
    right: 0;
    z-index: 95;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 20px 0 0 20px;
    padding: 10px 12px 10px 14px;
    cursor: pointer;
    color: var(--accent);
    box-shadow: var(--shadow-md);
  }

  .mobile-nav-icon { width: 20px; height: 20px; display: block; }

  .main-content { width: 100%; }

  .content-wrap { padding: 20px 16px 48px; }

  .main-header { padding: 12px 16px 0; }

  .stat-grid { grid-template-columns: repeat(2, 1fr); gap: 8px; }

  .topic-nav-prev, .topic-nav-next {
    display: block;
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    text-align: center;
    background: var(--surface);
    font-size: 14px;
  }
  .topic-nav-next { margin-left: 0; }
  .topic-nav-footer { flex-direction: column; }

  h1, h2 { font-size: 22px; }
  h3 { font-size: 17px; }
}

@media (min-width: 768px) {
  .mobile-nav-toggle { display: none; }
  #sidebar-overlay   { display: none !important; }
}