:root {
  color-scheme: light;
  --bg: #f4f6f3;
  --surface: #ffffff;
  --surface-soft: #eef3ef;
  --surface-strong: #e2ebe5;
  --text: #14211c;
  --muted: #5d6d65;
  --line: #d7e0da;
  --accent: #176b50;
  --accent-strong: #0f4c39;
  --accent-soft: #d9f1e6;
  --warn: #8b5b13;
  --warn-soft: #fff0cf;
  --danger: #9a3636;
  --danger-soft: #ffe4e4;
  --code-bg: #111a25;
  --code-text: #e6edf3;
  --shadow: 0 14px 40px rgba(26, 45, 36, 0.08);
  --sidebar: 292px;
  --radius: 18px;
  --mono: "Cascadia Code", "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans TC", sans-serif;
}

body[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0b1210;
  --surface: #111c18;
  --surface-soft: #15241e;
  --surface-strong: #1b3027;
  --text: #e8f0eb;
  --muted: #a2b3aa;
  --line: #294038;
  --accent: #6ad2a6;
  --accent-strong: #a7e3c5;
  --accent-soft: #173d30;
  --warn: #f0c36d;
  --warn-soft: #3d3017;
  --danger: #ff9b9b;
  --danger-soft: #3c2020;
  --code-bg: #07100d;
  --code-text: #e7f5ee;
  --shadow: 0 14px 50px rgba(0, 0, 0, 0.28);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  line-height: 1.72;
}
button, input, select { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: var(--accent); }
code { font-family: var(--mono); }

.skip-link {
  position: fixed;
  z-index: 1000;
  top: 10px;
  left: 10px;
  transform: translateY(-150%);
  padding: 8px 12px;
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
}
.skip-link:focus { transform: translateY(0); }

.app-layout { min-height: 100vh; }
.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: 40;
  width: var(--sidebar);
  overflow-y: auto;
  border-right: 1px solid var(--line);
  background: color-mix(in srgb, var(--surface) 94%, transparent);
  backdrop-filter: blur(16px);
  padding: 22px 18px 28px;
}
.brand {
  display: grid;
  grid-template-columns: 44px 1fr;
  gap: 12px;
  align-items: center;
  color: var(--text);
  text-decoration: none;
}
.brand-mark {
  display: grid;
  width: 44px;
  height: 44px;
  place-items: center;
  border-radius: 14px;
  background: #10231d;
  box-shadow: var(--shadow);
}
.brand-mark svg { width: 30px; height: 30px; }
.brand strong { display: block; font-size: 0.98rem; line-height: 1.25; }
.brand small { display: block; color: var(--muted); font-size: 0.74rem; }

.progress-panel {
  margin: 20px 0 18px;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface-soft);
}
.progress-row { display: flex; justify-content: space-between; gap: 10px; font-size: 0.82rem; }
.progress-track { height: 7px; margin-top: 9px; overflow: hidden; border-radius: 99px; background: var(--surface-strong); }
.progress-fill { height: 100%; border-radius: inherit; background: var(--accent); transition: width .25s ease; }

.nav-group-title {
  margin: 20px 10px 7px;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: .11em;
  text-transform: uppercase;
}
.side-nav { display: grid; gap: 3px; }
.side-link {
  display: grid;
  grid-template-columns: 26px 1fr auto;
  gap: 8px;
  align-items: center;
  min-height: 42px;
  padding: 8px 10px;
  border-radius: 11px;
  color: var(--muted);
  text-decoration: none;
  font-size: 0.88rem;
  line-height: 1.3;
}
.side-link:hover { background: var(--surface-soft); color: var(--text); }
.side-link.active { background: var(--accent-soft); color: var(--accent-strong); font-weight: 750; }
.side-link .index { color: var(--muted); font-family: var(--mono); font-size: 0.72rem; }
.side-link .done { color: var(--accent); font-size: .82rem; }
.sidebar-footer { margin-top: 22px; padding: 12px 10px; color: var(--muted); font-size: 0.75rem; }

.main-wrap { margin-left: var(--sidebar); min-height: 100vh; }
.topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  gap: 12px;
  min-height: 68px;
  padding: 10px clamp(18px, 4vw, 48px);
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(18px);
}
.menu-button { display: none; }
.search-wrap { position: relative; flex: 1; max-width: 720px; }
.search-input {
  width: 100%;
  min-height: 43px;
  padding: 9px 44px 9px 42px;
  border: 1px solid var(--line);
  border-radius: 12px;
  outline: none;
  background: var(--surface);
  color: var(--text);
}
.search-input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 18%, transparent); }
.search-icon { position: absolute; left: 14px; top: 10px; color: var(--muted); }
.search-shortcut { position: absolute; right: 10px; top: 9px; padding: 2px 7px; border: 1px solid var(--line); border-radius: 6px; color: var(--muted); font-size: .72rem; }
.search-results {
  position: absolute;
  z-index: 80;
  top: 50px;
  right: 0;
  left: 0;
  max-height: 62vh;
  overflow-y: auto;
  padding: 8px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface);
  box-shadow: var(--shadow);
}
.search-results[hidden] { display: none; }
.search-result { display: block; padding: 10px 12px; border-radius: 9px; color: var(--text); text-decoration: none; }
.search-result:hover { background: var(--surface-soft); }
.search-result small { display: block; color: var(--muted); }
.icon-button, .menu-button {
  display: inline-grid;
  width: 42px;
  height: 42px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
}

.content { width: min(1160px, calc(100% - 36px)); margin: 0 auto; padding: clamp(28px, 5vw, 64px) 0 96px; }
.hero {
  position: relative;
  overflow: hidden;
  padding: clamp(28px, 5vw, 58px);
  border: 1px solid var(--line);
  border-radius: 28px;
  background:
    radial-gradient(circle at 88% 18%, color-mix(in srgb, var(--accent) 20%, transparent), transparent 33%),
    linear-gradient(135deg, var(--surface), var(--surface-soft));
  box-shadow: var(--shadow);
}
.hero::after {
  content: "TS";
  position: absolute;
  right: 4%;
  bottom: -22%;
  color: color-mix(in srgb, var(--accent) 9%, transparent);
  font: 900 clamp(8rem, 22vw, 18rem)/1 var(--mono);
  pointer-events: none;
}
.eyebrow { display: inline-flex; gap: 8px; align-items: center; color: var(--accent); font-size: .78rem; font-weight: 850; letter-spacing: .1em; text-transform: uppercase; }
.hero h1, .chapter-header h1 { max-width: 920px; margin: 14px 0 16px; font-size: clamp(2.15rem, 5vw, 4.6rem); line-height: 1.06; letter-spacing: -.045em; }
.hero p { max-width: 760px; margin: 0; color: var(--muted); font-size: clamp(1rem, 2vw, 1.18rem); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 28px; position: relative; z-index: 1; }
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 9px 16px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  text-decoration: none;
  font-weight: 750;
  cursor: pointer;
}
.button.primary { border-color: var(--accent); background: var(--accent); color: #fff; }
body[data-theme="dark"] .button.primary { color: #092017; }
.button.ghost { background: transparent; }
.button:hover { transform: translateY(-1px); }

.stat-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 14px; margin: 22px 0 0; }
.stat-card, .card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: 0 5px 20px rgba(20, 40, 31, .04);
}
.stat-card { padding: 18px; }
.stat-card strong { display: block; font: 800 clamp(1.35rem, 3vw, 2rem)/1.2 var(--mono); }
.stat-card span { display: block; margin-top: 5px; color: var(--muted); font-size: .82rem; }

.section-heading { margin: 50px 0 18px; }
.section-heading h2 { margin: 0; font-size: clamp(1.5rem, 3vw, 2.2rem); letter-spacing: -.025em; }
.section-heading p { margin: 5px 0 0; color: var(--muted); }
.card-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.card { padding: 20px; }
.card h3 { margin: 0 0 8px; font-size: 1.05rem; }
.card p { margin: 0; color: var(--muted); font-size: .92rem; }
.card-link { display: block; color: inherit; text-decoration: none; transition: transform .18s ease, border-color .18s ease; }
.card-link:hover { transform: translateY(-3px); border-color: var(--accent); }
.card-meta { display: flex; justify-content: space-between; gap: 8px; margin-top: 18px; color: var(--muted); font-size: .75rem; }
.badge { display: inline-flex; align-items: center; gap: 5px; padding: 3px 8px; border-radius: 99px; background: var(--surface-soft); color: var(--muted); font-size: .72rem; font-weight: 750; }
.badge.accent { background: var(--accent-soft); color: var(--accent-strong); }

.chapter-header { padding-bottom: 28px; border-bottom: 1px solid var(--line); }
.chapter-header h1 { font-size: clamp(2rem, 4.5vw, 3.8rem); }
.chapter-lead { max-width: 820px; color: var(--muted); font-size: 1.08rem; }
.chapter-meta { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 18px; }
.objectives { margin: 26px 0; padding: 20px 22px; border-left: 4px solid var(--accent); border-radius: 0 16px 16px 0; background: var(--accent-soft); }
.objectives h2 { margin: 0 0 8px; font-size: 1rem; }
.objectives ul { margin: 0; padding-left: 1.25rem; }
.lesson-section { max-width: 900px; margin: 42px 0; }
.lesson-section h2 { margin: 0 0 12px; font-size: clamp(1.35rem, 2.7vw, 1.85rem); letter-spacing: -.02em; }
.lesson-section h3 { margin: 28px 0 8px; font-size: 1.12rem; }
.lesson-section p, .lesson-section li { color: color-mix(in srgb, var(--text) 85%, var(--muted)); }
.lesson-section table { width: 100%; border-collapse: collapse; margin: 18px 0; font-size: .9rem; }
.lesson-section th, .lesson-section td { padding: 11px 12px; border: 1px solid var(--line); text-align: left; vertical-align: top; }
.lesson-section th { background: var(--surface-soft); }

.callout { margin: 20px 0; padding: 16px 18px; border: 1px solid var(--line); border-radius: 14px; background: var(--surface-soft); }
.callout strong { display: block; margin-bottom: 4px; }
.callout.warning { border-color: color-mix(in srgb, var(--warn) 50%, var(--line)); background: var(--warn-soft); }
.callout.danger { border-color: color-mix(in srgb, var(--danger) 50%, var(--line)); background: var(--danger-soft); }
.file-chip { display: inline-flex; align-items: center; padding: 2px 8px; border: 1px solid var(--line); border-radius: 7px; background: var(--surface); font: 600 .82rem/1.6 var(--mono); }
.file-list { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0; }

.code-shell { position: relative; margin: 20px 0; overflow: hidden; border: 1px solid #243348; border-radius: 15px; background: var(--code-bg); box-shadow: var(--shadow); }
.code-head { display: flex; justify-content: space-between; align-items: center; gap: 10px; padding: 8px 12px; border-bottom: 1px solid #243348; color: #9fb0c4; font: 600 .72rem/1.4 var(--mono); }
.copy-button { border: 0; background: transparent; color: #b9c8d8; cursor: pointer; font: inherit; }
.code-shell pre { margin: 0; padding: 17px; overflow-x: auto; color: var(--code-text); font: 500 .84rem/1.65 var(--mono); tab-size: 2; }
.inline-code { padding: 2px 6px; border-radius: 6px; background: var(--surface-strong); color: var(--accent-strong); font-family: var(--mono); font-size: .9em; }

.flow { display: grid; gap: 10px; margin: 20px 0; }
.flow-step { position: relative; display: grid; grid-template-columns: 36px 1fr; gap: 12px; align-items: start; padding: 14px 16px; border: 1px solid var(--line); border-radius: 14px; background: var(--surface); }
.flow-step:not(:last-child)::after { content: "↓"; position: absolute; bottom: -22px; left: 25px; z-index: 2; color: var(--accent); font-weight: 900; }
.flow-index { display: grid; width: 30px; height: 30px; place-items: center; border-radius: 9px; background: var(--accent-soft); color: var(--accent-strong); font: 800 .78rem var(--mono); }
.flow-step strong { display: block; }
.flow-step small { color: var(--muted); }

.architecture-board { position: relative; display: grid; gap: 14px; padding: 22px; border: 1px solid var(--line); border-radius: 22px; background: linear-gradient(135deg, var(--surface), var(--surface-soft)); }
.arch-row { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; }
.arch-row.single { grid-template-columns: minmax(0, 1fr); max-width: 520px; width: 100%; margin: 0 auto; }
.arch-node { min-height: 112px; padding: 16px; border: 1px solid var(--line); border-radius: 15px; background: var(--surface); color: var(--text); text-align: left; cursor: pointer; }
.arch-node:hover, .arch-node.selected { border-color: var(--accent); box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 13%, transparent); }
.arch-node strong { display: block; margin-bottom: 6px; }
.arch-node small { color: var(--muted); }
.arch-arrow { text-align: center; color: var(--accent); font-size: 1.35rem; font-weight: 900; }
.arch-detail { margin-top: 18px; padding: 20px; border: 1px solid var(--line); border-radius: 16px; background: var(--surface); }

.quiz { max-width: 900px; margin: 44px 0; padding: 22px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
.quiz h2 { margin-top: 0; }
.quiz-option { display: block; margin: 9px 0; padding: 11px 13px; border: 1px solid var(--line); border-radius: 11px; cursor: pointer; }
.quiz-option:hover { border-color: var(--accent); }
.quiz-feedback { margin-top: 12px; padding: 11px 13px; border-radius: 10px; background: var(--surface-soft); }
.quiz-feedback.correct { background: var(--accent-soft); color: var(--accent-strong); }
.quiz-feedback.wrong { background: var(--danger-soft); color: var(--danger); }
.chapter-actions { display: flex; flex-wrap: wrap; gap: 10px; justify-content: space-between; max-width: 900px; padding-top: 26px; border-top: 1px solid var(--line); }

.toolbar { display: flex; flex-wrap: wrap; gap: 10px; margin: 18px 0 22px; }
.toolbar input, .toolbar select { min-height: 42px; padding: 8px 12px; border: 1px solid var(--line); border-radius: 11px; background: var(--surface); color: var(--text); }
.toolbar input { flex: 1; min-width: 230px; }
.locator-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 15px; }
.locator-card { padding: 20px; border: 1px solid var(--line); border-radius: 17px; background: var(--surface); }
.locator-card h3 { margin: 0 0 8px; }
.locator-card p { color: var(--muted); }
.locator-card dl { display: grid; grid-template-columns: 100px 1fr; gap: 8px 12px; margin: 16px 0 0; font-size: .86rem; }
.locator-card dt { color: var(--muted); font-weight: 750; }
.locator-card dd { margin: 0; }

.glossary-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.glossary-item { padding: 17px; border: 1px solid var(--line); border-radius: 14px; background: var(--surface); }
.glossary-item h3 { display: flex; align-items: baseline; gap: 8px; margin: 0 0 6px; font-size: 1rem; }
.glossary-item h3 code { color: var(--accent); }
.glossary-item p { margin: 0; color: var(--muted); font-size: .9rem; }

.checklist { display: grid; gap: 10px; max-width: 860px; }
.check-item { display: grid; grid-template-columns: 24px 1fr; gap: 12px; padding: 14px; border: 1px solid var(--line); border-radius: 13px; background: var(--surface); }
.check-item input { width: 18px; height: 18px; margin-top: 4px; accent-color: var(--accent); }
.check-item strong { display: block; }
.check-item small { color: var(--muted); }

.source-list { display: grid; gap: 9px; margin-top: 24px; }
.source-link { display: grid; grid-template-columns: 1fr auto; gap: 10px; padding: 12px 14px; border: 1px solid var(--line); border-radius: 12px; background: var(--surface); color: var(--text); text-decoration: none; }
.source-link small { display: block; color: var(--muted); }

.empty-state { padding: 30px; border: 1px dashed var(--line); border-radius: 16px; color: var(--muted); text-align: center; }
.mobile-overlay { display: none; }
.build-stamp { margin-left: var(--sidebar); padding: 16px 32px 28px; color: var(--muted); text-align: center; font-size: .72rem; }

@media (max-width: 1040px) {
  .stat-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .card-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 820px) {
  :root { --sidebar: 286px; }
  .sidebar { transform: translateX(-105%); transition: transform .22s ease; box-shadow: var(--shadow); }
  body.sidebar-open .sidebar { transform: translateX(0); }
  .mobile-overlay { position: fixed; z-index: 35; inset: 0; background: rgba(0,0,0,.32); }
  body.sidebar-open .mobile-overlay { display: block; }
  .main-wrap, .build-stamp { margin-left: 0; }
  .menu-button { display: inline-grid; }
  .content { width: min(100% - 26px, 1160px); }
  .topbar { padding-inline: 13px; }
  .search-shortcut { display: none; }
  .arch-row { grid-template-columns: 1fr; }
}

@media (max-width: 620px) {
  .hero { padding: 25px 21px; border-radius: 22px; }
  .hero h1 { font-size: 2.25rem; }
  .stat-grid, .card-grid, .locator-grid, .glossary-grid { grid-template-columns: 1fr; }
  .chapter-header h1 { font-size: 2.2rem; }
  .lesson-section table { display: block; overflow-x: auto; }
  .locator-card dl { grid-template-columns: 1fr; gap: 2px; }
  .locator-card dd { margin-bottom: 9px; }
  .chapter-actions { flex-direction: column; }
  .chapter-actions .button { width: 100%; }
}

@media print {
  .sidebar, .topbar, .chapter-actions, .copy-button, .build-stamp { display: none !important; }
  .main-wrap { margin: 0; }
  .content { width: 100%; padding: 0; }
  .card, .quiz, .callout, .code-shell { break-inside: avoid; box-shadow: none; }
  body { background: #fff; color: #111; }
}

/* Project screenshots */
.visual-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(280px, .65fr);
  gap: 18px;
  align-items: start;
}
.visual-stack { display: grid; gap: 18px; }
.lesson-figure {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow);
}
.lesson-figure img { display: block; width: 100%; height: auto; background: var(--surface-soft); }
.lesson-figure figcaption { padding: 12px 15px; color: var(--muted); font-size: .84rem; }
.visual-stack .lesson-figure img { max-height: 430px; object-fit: contain; }
@media (max-width: 760px) {
  .visual-grid { grid-template-columns: 1fr; }
  .visual-stack { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 500px) {
  .visual-stack { grid-template-columns: 1fr; }
}