:root {
  --bg: #0b1020;
  --panel: rgba(15, 22, 42, 0.82);
  --panel-strong: #17203a;
  --line: rgba(255, 255, 255, 0.09);
  --text: #ebf0ff;
  --muted: #a9b4d0;
  --accent: #7c9cff;
  --accent-strong: #5f7ef7;
  --accent-soft: rgba(124, 156, 255, 0.18);
  --success: #60d394;
  --danger: #ff7b7b;
  --shadow: 0 24px 60px rgba(0, 0, 0, 0.32);
  --radius-xl: 24px;
  --radius-lg: 18px;
  --radius-md: 14px;
  --max-width: 1600px;
}

body.light-theme {
  --bg: #f4f7ff;
  --panel: rgba(255, 255, 255, 0.93);
  --panel-strong: #ffffff;
  --line: rgba(21, 31, 61, 0.12);
  --text: #17203a;
  --muted: #55607d;
  --accent: #4867f8;
  --accent-strong: #314ee0;
  --accent-soft: rgba(72, 103, 248, 0.12);
  --success: #1d9a5a;
  --danger: #cf4c4c;
  --shadow: 0 20px 40px rgba(42, 63, 120, 0.10);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Inter", system-ui, sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(124, 156, 255, 0.14), transparent 32%),
    radial-gradient(circle at top right, rgba(96, 211, 148, 0.1), transparent 28%),
    var(--bg);
}

body.light-theme {
  background:
    radial-gradient(circle at top left, rgba(72, 103, 248, 0.10), transparent 34%),
    radial-gradient(circle at top right, rgba(29, 154, 90, 0.08), transparent 30%),
    var(--bg);
}

::selection {
  background: var(--accent-soft);
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: auto;
}

.skip-link:focus {
  left: 20px;
  top: 20px;
  z-index: 1000;
  padding: 10px 14px;
  border-radius: 12px;
  background: var(--panel-strong);
  color: var(--text);
  border: 1px solid var(--line);
}

.app-shell {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 28px;
}

.topbar {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  align-items: flex-start;
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}

.eyebrow,
.section-tag,
.nav-group-title {
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.75rem;
  color: var(--muted);
  margin: 0 0 10px;
}

.brand-block h1,
.hero h2,
.section-heading h2,
.card-header h3 {
  margin: 0;
  line-height: 1.05;
}

.brand-block h1 {
  font-size: clamp(2rem, 4vw, 3.6rem);
}

.subtitle {
  max-width: 55ch;
  margin: 14px 0 0;
  color: var(--muted);
  line-height: 1.7;
}

.topbar-actions {
  display: flex;
  gap: 16px;
  align-items: center;
}

.status-card,
.theme-toggle {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel-strong);
}

.status-card {
  min-width: 260px;
  padding: 16px;
}

.status-meta {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 10px;
  color: var(--muted);
}

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

.status-hint {
  margin: 0;
  color: var(--muted);
  line-height: 1.6;
  font-size: 0.95rem;
}

.theme-toggle {
  display: inline-flex;
  gap: 10px;
  align-items: center;
  padding: 16px 18px;
  color: var(--text);
  cursor: pointer;
  font: inherit;
  transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}

.theme-toggle:hover,
.theme-toggle:focus-visible,
.btn:hover,
.btn:focus-visible,
.copy-btn:hover,
.copy-btn:focus-visible,
.accordion:hover,
.accordion:focus-visible {
  outline: none;
  border-color: rgba(124, 156, 255, 0.35);
  transform: translateY(-1px);
}

.layout {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  gap: 24px;
  margin-top: 24px;
}

.sidebar {
  position: sticky;
  top: 24px;
  align-self: start;
}

.chapter-nav {
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  padding: 22px;
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}

.nav-group + .nav-group {
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.nav-link {
  display: block;
  color: var(--muted);
  text-decoration: none;
  padding: 10px 12px;
  border-radius: 12px;
  transition: background 180ms ease, color 180ms ease, transform 180ms ease;
}

.nav-link:hover,
.nav-link.active {
  background: var(--accent-soft);
  color: var(--text);
  transform: translateX(3px);
}

.nav-link--sub {
  padding-left: 22px;
  font-size: 0.96rem;
}

.content {
  display: flex;
  flex-direction: column;
  gap: 26px;
}

.section-block {
  display: flex;
  flex-direction: column;
  gap: 22px;
}

.section-heading {
  padding: 6px 4px 0;
}

.section-heading p:last-child {
  max-width: 70ch;
  color: var(--muted);
  line-height: 1.7;
}

.section-card {
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  padding: 28px;
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
  opacity: 0.74;
  transform: translateY(12px);
  transition: opacity 220ms ease, transform 220ms ease, border-color 220ms ease;
}

.visible-section,
.section-card.in-view {
  opacity: 1;
  transform: translateY(0);
  border-color: rgba(124, 156, 255, 0.25);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(320px, 0.95fr);
  gap: 24px;
  align-items: center;
}

.pill {
  display: inline-flex;
  align-items: center;
  padding: 8px 12px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--text);
  font-weight: 600;
  margin-bottom: 16px;
}

.hero h2 {
  font-size: clamp(2rem, 3vw, 3.2rem);
}

.hero p {
  color: var(--muted);
  line-height: 1.8;
  max-width: 60ch;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 22px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 18px;
  border-radius: 14px;
  text-decoration: none;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  font: inherit;
  transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: white;
}

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

.comparison-card,
.info-box,
.checklist-card,
.note-box,
.mode-card,
.role-card,
.tool-card,
.warning-card,
.pitfall-item,
.lesson-card,
.prompt-block,
.architecture-main,
.architecture-side {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel-strong);
}

.comparison-card,
.checklist-card,
.note-box,
.prompt-block {
  padding: 20px;
}

.comparison-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.comparison-grid--wide {
  margin-top: 18px;
}

.comparison-grid article,
.mode-card,
.lesson-card,
.role-card,
.tool-card,
.warning-card,
.pitfall-item {
  padding: 18px;
}

.comparison-grid h4,
.mode-card h4,
.role-card h4,
.tool-card h4,
.warning-card h4,
.pitfall-item h4,
.lesson-card h4,
.info-box h4,
.prompt-head h4,
.architecture-main h4 {
  margin-top: 0;
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 18px;
}

.step-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 42px;
  height: 42px;
  border-radius: 12px;
  background: var(--accent-soft);
  color: var(--text);
  font-weight: 800;
}

.info-grid.two-col,
.warning-grid,
.lesson-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.info-box {
  padding: 20px;
}

.info-box.emphasis {
  background: linear-gradient(180deg, var(--accent-soft), transparent), var(--panel-strong);
}

.note-box {
  margin-top: 18px;
  line-height: 1.7;
}

.note-box--soft {
  background: linear-gradient(180deg, rgba(96, 211, 148, 0.08), transparent), var(--panel-strong);
}

.orchestra-diagram {
  margin: 24px 0;
  display: flex;
  flex-direction: column;
  gap: 18px;
  align-items: center;
}

.node-row {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
  width: 100%;
}

.node {
  text-align: center;
  padding: 18px 16px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--line);
  background: var(--panel-strong);
  font-weight: 600;
}

.node-head {
  min-width: min(460px, 100%);
  background: linear-gradient(135deg, var(--accent-soft), transparent), var(--panel-strong);
}

.node-head span {
  display: block;
  margin-top: 8px;
  font-size: 0.95rem;
  color: var(--muted);
  font-weight: 500;
}

.accordion-set {
  margin-top: 22px;
}

.accordion {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 18px;
  padding: 18px 20px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--line);
  background: var(--panel-strong);
  color: var(--text);
  cursor: pointer;
  font: inherit;
  text-align: left;
  transition: border-color 160ms ease, transform 160ms ease;
}

.accordion-icon {
  flex: 0 0 auto;
  font-size: 1.5rem;
  line-height: 1;
}

.accordion-panel {
  max-height: 0;
  overflow: hidden;
  transition: max-height 240ms ease, padding 240ms ease;
  padding: 0 18px;
}

.accordion-panel.open {
  padding: 18px;
}

.role-grid,
.tool-grid,
.pitfall-list,
.architecture-grid {
  display: grid;
  gap: 18px;
}

.role-grid,
.tool-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.timeline {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: 14px;
}

.timeline-step {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel-strong);
  padding: 18px;
}

.timeline-step span {
  display: inline-flex;
  width: 32px;
  height: 32px;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  background: var(--accent-soft);
  font-weight: 800;
  margin-bottom: 12px;
}

.warning-card.danger {
  background: linear-gradient(180deg, rgba(255, 123, 123, 0.1), transparent), var(--panel-strong);
}

.architecture-grid {
  grid-template-columns: 1.2fr repeat(2, minmax(0, 1fr));
}

.architecture-main,
.architecture-side {
  padding: 22px;
}

.architecture-main {
  grid-row: span 3;
  background: linear-gradient(180deg, var(--accent-soft), transparent), var(--panel-strong);
}

.pipeline {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  margin-bottom: 18px;
}

.pipeline-step,
.pipeline-arrow {
  padding: 14px 18px;
  border-radius: 14px;
}

.pipeline-step {
  border: 1px solid var(--line);
  background: var(--panel-strong);
  font-weight: 600;
}

.pipeline-arrow {
  color: var(--muted);
  font-weight: 800;
}

.prompt-block + .prompt-block {
  margin-top: 18px;
}

.prompt-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
  margin-bottom: 14px;
}

pre {
  margin: 0;
  white-space: pre-wrap;
  word-break: break-word;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  line-height: 1.65;
  color: var(--text);
}

.copy-btn {
  padding: 10px 14px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--text);
  cursor: pointer;
  font: inherit;
  transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}

.toast {
  position: fixed;
  right: 24px;
  bottom: 24px;
  padding: 14px 18px;
  border-radius: 14px;
  background: #11192f;
  color: white;
  box-shadow: var(--shadow);
  opacity: 0;
  transform: translateY(10px);
  pointer-events: none;
  transition: opacity 180ms ease, transform 180ms ease;
  z-index: 2000;
}

.toast.show {
  opacity: 1;
  transform: translateY(0);
}

ul {
  padding-left: 1.2rem;
}

li,
p {
  line-height: 1.75;
}

@media (max-width: 1200px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
  }

  .hero,
  .role-grid,
  .tool-grid,
  .architecture-grid,
  .node-row {
    grid-template-columns: 1fr 1fr;
  }

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

@media (max-width: 860px) {
  .app-shell {
    padding: 16px;
  }

  .topbar {
    padding: 20px;
    flex-direction: column;
  }

  .topbar-actions {
    display: grid;
    width: 100%;
  }

  .status-card,
  .theme-toggle {
    width: 100%;
  }

  .hero,
  .comparison-grid,
  .info-grid.two-col,
  .warning-grid,
  .lesson-grid,
  .role-grid,
  .tool-grid,
  .timeline,
  .architecture-grid,
  .node-row {
    grid-template-columns: 1fr;
  }

  .pipeline {
    flex-direction: column;
    align-items: stretch;
  }

  .pipeline-arrow {
    text-align: center;
  }

  .prompt-head {
    flex-direction: column;
    align-items: stretch;
  }
}