/* =========================================================
   Federal Data Science Learning Handbook — Main Stylesheet
   Modern editorial design with platform color palette
   ========================================================= */

/* --- Design Tokens --- */
:root {
  /* Platform Colors */
  --palantir-blue: #1B2A4A;
  --databricks-red: #FF3621;
  --qlik-green: #009845;
  --jupiter-navy: #003B5C;
  --advana-gold: #C5A572;

  /* Semantic Colors (Light Mode) */
  --bg-primary: #FAFAF8;
  --bg-secondary: #F4F3EF;
  --bg-card: #FFFFFF;
  --bg-code: #F1F0EC;
  --bg-sidebar: #FFFFFF;
  --bg-nav: rgba(250, 250, 248, 0.95);
  --bg-hero: #1B2A4A;

  --text-primary: #1A1A1A;
  --text-secondary: #4A4A4A;
  --text-muted: #767676;
  --text-inverse: #FAFAF8;
  --text-accent: #1B2A4A;
  --text-link: #003B5C;
  --text-link-hover: #FF3621;

  --border-light: #E8E7E3;
  --border-medium: #D0CEC8;
  --border-accent: #C5A572;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 16px 40px rgba(0,0,0,0.10), 0 4px 12px rgba(0,0,0,0.06);

  /* Typography */
  --font-serif: 'Georgia', 'Times New Roman', serif;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Inter', 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SFMono-Regular', 'Fira Code', 'Cascadia Code', 'Consolas', 'Liberation Mono', monospace;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;
  --text-6xl: 3.75rem;

  --leading-tight: 1.25;
  --leading-snug: 1.375;
  --leading-normal: 1.6;
  --leading-relaxed: 1.75;
  --leading-loose: 1.9;

  /* Layout */
  --sidebar-width: 260px;
  --content-max: 72ch;
  --nav-height: 64px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.25s ease;
  --transition-slow: 0.4s ease;
}

/* --- Dark Mode --- */
[data-theme="dark"] {
  --bg-primary: #0F1117;
  --bg-secondary: #161B26;
  --bg-card: #1C2333;
  --bg-code: #161B26;
  --bg-sidebar: #131720;
  --bg-nav: rgba(15, 17, 23, 0.96);
  --bg-hero: #080D16;

  --text-primary: #E8E6DF;
  --text-secondary: #B8B4A8;
  --text-muted: #7A7670;
  --text-inverse: #1A1A1A;
  --text-accent: #C5A572;
  --text-link: #7EB3D4;
  --text-link-hover: #FF6B55;

  --border-light: #252B3A;
  --border-medium: #2E3649;
  --border-accent: #C5A572;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3), 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4), 0 2px 4px rgba(0,0,0,0.2);
  --shadow-lg: 0 16px 40px rgba(0,0,0,0.5), 0 4px 12px rgba(0,0,0,0.3);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color var(--transition-base), color var(--transition-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--text-link);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--text-link-hover);
}

img {
  max-width: 100%;
  height: auto;
}

/* --- Top Navigation --- */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--bg-nav);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-light);
  z-index: 100;
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  gap: 1rem;
  transition: background-color var(--transition-base), border-color var(--transition-base);
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--text-primary);
  text-decoration: none;
  flex-shrink: 0;
}

.nav-brand-icon {
  width: 28px;
  height: 28px;
  flex-shrink: 0;
}

.nav-brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}

.nav-brand-title {
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.nav-brand-subtitle {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--text-primary);
}

.nav-spacer {
  flex: 1;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  list-style: none;
}

.nav-links a {
  display: block;
  padding: 0.375rem 0.75rem;
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-secondary);
  border-radius: 6px;
  transition: color var(--transition-fast), background var(--transition-fast);
}

.nav-links a:hover {
  color: var(--text-primary);
  background: var(--bg-secondary);
}

.nav-links a.active {
  color: var(--palantir-blue);
  background: rgba(27,42,74,0.08);
}

[data-theme="dark"] .nav-links a.active {
  color: var(--advana-gold);
  background: rgba(197,165,114,0.12);
}

/* ======================================================
   NAV DROPDOWN
   ====================================================== */
.nav-dropdown {
  position: relative;
}

.nav-dropdown-toggle {
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.nav-dropdown-toggle::after {
  content: '';
  display: inline-block;
  width: 0;
  height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-top: 4px solid currentColor;
  margin-top: 2px;
}

.nav-dropdown-menu {
  display: none;
  position: absolute;
  top: 100%;
  right: 0;
  min-width: 200px;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  padding: 0.5rem 0;
  z-index: 100;
  margin-top: 0.5rem;
}

.nav-dropdown:hover .nav-dropdown-menu,
.nav-dropdown:focus-within .nav-dropdown-menu {
  display: block;
}

.nav-dropdown-menu a {
  display: block;
  padding: 0.5rem 1rem;
  color: var(--text-primary);
  text-decoration: none;
  font-size: 0.875rem;
  transition: background 0.15s ease;
}

.nav-dropdown-menu a:hover {
  background: var(--bg-secondary);
}

[data-theme="dark"] .nav-dropdown-menu {
  box-shadow: 0 4px 12px rgba(0,0,0,0.3);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: color var(--transition-fast), background var(--transition-fast);
}

.btn-icon:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.btn-icon svg {
  width: 18px;
  height: 18px;
}

.mobile-menu-btn {
  display: none;
}

/* --- Sidebar --- */
.sidebar {
  position: fixed;
  top: var(--nav-height);
  left: 0;
  width: var(--sidebar-width);
  height: calc(100vh - var(--nav-height));
  overflow-y: auto;
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border-light);
  padding: 1.5rem 0;
  transition: transform var(--transition-base), background-color var(--transition-base);
  z-index: 50;
}

.sidebar::-webkit-scrollbar {
  width: 4px;
}

.sidebar::-webkit-scrollbar-track {
  background: transparent;
}

.sidebar::-webkit-scrollbar-thumb {
  background: var(--border-medium);
  border-radius: 4px;
}

.sidebar-section {
  margin-bottom: 1.75rem;
}

.sidebar-label {
  display: block;
  padding: 0 1.25rem 0.5rem;
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.sidebar-nav {
  list-style: none;
}

.sidebar-nav li a {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  padding: 0.4rem 1.25rem;
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: var(--leading-snug);
  border-right: 2px solid transparent;
  transition: color var(--transition-fast), background var(--transition-fast), border-color var(--transition-fast);
}

.sidebar-nav li a:hover {
  color: var(--text-primary);
  background: var(--bg-secondary);
}

.sidebar-nav li a.active {
  color: var(--palantir-blue);
  border-right-color: var(--palantir-blue);
  background: rgba(27,42,74,0.06);
  font-weight: 600;
}

[data-theme="dark"] .sidebar-nav li a.active {
  color: var(--advana-gold);
  border-right-color: var(--advana-gold);
  background: rgba(197,165,114,0.1);
}

.sidebar-nav .chapter-num {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-muted);
  font-family: var(--font-mono);
  min-width: 24px;
}

.platform-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

/* --- Main Layout --- */
.page-wrapper {
  display: flex;
  padding-top: var(--nav-height);
}

.main-content {
  margin-left: var(--sidebar-width);
  flex: 1;
  min-width: 0;
}

.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.4);
  z-index: 40;
}

/* =========================================================
   HOME PAGE STYLES
   ========================================================= */

/* --- Hero Section --- */
.hero {
  background: var(--bg-hero);
  color: var(--text-inverse);
  padding: 5rem 4rem 4rem;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(197,165,114,0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -30%;
  left: -10%;
  width: 400px;
  height: 400px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(0,152,69,0.06) 0%, transparent 70%);
  pointer-events: none;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--advana-gold);
  margin-bottom: 1.25rem;
}

.hero-eyebrow-line {
  width: 24px;
  height: 1px;
  background: var(--advana-gold);
  display: block;
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(2rem, 4vw, var(--text-5xl));
  font-weight: 400;
  line-height: var(--leading-tight);
  letter-spacing: -0.02em;
  color: #FFFFFF;
  max-width: 20ch;
  margin-bottom: 1.5rem;
}

.hero-title em {
  font-style: italic;
  color: var(--advana-gold);
}

.hero-description {
  font-size: var(--text-lg);
  line-height: var(--leading-relaxed);
  color: rgba(255,255,255,0.72);
  max-width: 60ch;
  margin-bottom: 2.5rem;
}

.hero-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 2rem;
  margin-bottom: 3rem;
}

.stat-item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  /* UX-008: Prevents horizontal overflow on tablet breakpoints when flex-wrap kicks in */
  min-width: 0;
}

.stat-value {
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: 700;
  color: #FFFFFF;
  line-height: 1;
}

.stat-label {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  /* UX-014: Increased opacity from 0.5 to 0.65 for WCAG AA contrast (~4.7:1) */
  color: rgba(255,255,255,0.65);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  font-size: var(--text-sm);
  font-weight: 600;
  background: var(--advana-gold);
  color: #1A1A1A;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  text-decoration: none;
  transition: background var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
}

.btn-primary:hover {
  background: #D4B483;
  color: #1A1A1A;
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(197,165,114,0.4);
}

/* btn-primary in dark mode: white text on gold for better contrast */
[data-theme="dark"] .btn-primary {
  color: #0F1117;
}

[data-theme="dark"] .btn-primary:hover {
  color: #0F1117;
}

/* btn-secondary: hero context (dark bg) */
.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  font-size: var(--text-sm);
  font-weight: 600;
  background: rgba(255,255,255,0.08);
  color: rgba(255,255,255,0.9);
  border: 1px solid rgba(255,255,255,0.16);
  border-radius: 8px;
  cursor: pointer;
  text-decoration: none;
  transition: background var(--transition-fast), border-color var(--transition-fast);
}

.btn-secondary:hover {
  background: rgba(255,255,255,0.14);
  color: #FFFFFF;
  border-color: rgba(255,255,255,0.28);
}

/* btn-secondary on light backgrounds (outside hero) */
.prose .btn-secondary,
.exercises-callout .btn-secondary {
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-medium);
}

.prose .btn-secondary:hover,
.exercises-callout .btn-secondary:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border-color: var(--advana-gold);
}

.platform-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  padding: 1.5rem 4rem;
  background: rgba(0,0,0,0.12);
  border-bottom: 1px solid var(--border-light);
  align-items: center;
}

[data-theme="dark"] .platform-strip {
  background: rgba(0,0,0,0.3);
}

.platform-strip-label {
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-right: 0.5rem;
}

.platform-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  padding: 0.25rem 0.75rem;
  font-size: var(--text-xs);
  font-weight: 600;
  border-radius: 100px;
  border: 1px solid;
  text-decoration: none;
  transition: all var(--transition-fast);
}

.platform-badge:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.platform-badge.palantir {
  color: var(--palantir-blue);
  border-color: rgba(27,42,74,0.3);
  background: rgba(27,42,74,0.06);
}

.platform-badge.databricks {
  color: var(--databricks-red);
  border-color: rgba(255,54,33,0.3);
  background: rgba(255,54,33,0.06);
}

.platform-badge.qlik {
  color: var(--qlik-green);
  border-color: rgba(0,152,69,0.3);
  background: rgba(0,152,69,0.06);
}

.platform-badge.jupiter {
  color: var(--jupiter-navy);
  border-color: rgba(0,59,92,0.3);
  background: rgba(0,59,92,0.06);
}

.platform-badge.advana {
  color: #8B6914;
  border-color: rgba(197,165,114,0.4);
  background: rgba(197,165,114,0.1);
}

[data-theme="dark"] .platform-badge.palantir {
  color: #7EB3D4;
  border-color: rgba(126,179,212,0.3);
  background: rgba(126,179,212,0.08);
}

[data-theme="dark"] .platform-badge.databricks {
  color: #FF6B55;
  border-color: rgba(255,107,85,0.3);
  background: rgba(255,107,85,0.08);
}

[data-theme="dark"] .platform-badge.qlik {
  color: #4DC97A;
  border-color: rgba(77,201,122,0.3);
  background: rgba(77,201,122,0.08);
}

[data-theme="dark"] .platform-badge.jupiter {
  color: #5BA3C9;
  border-color: rgba(91,163,201,0.3);
  background: rgba(91,163,201,0.08);
}

[data-theme="dark"] .platform-badge.advana {
  color: var(--advana-gold);
  border-color: rgba(197,165,114,0.4);
  background: rgba(197,165,114,0.1);
}

/* --- Content Sections --- */
.section {
  padding: 4rem;
}

.section-alt {
  background: var(--bg-secondary);
}

.section-header {
  margin-bottom: 2.5rem;
}

.section-eyebrow {
  display: block;
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.section-title {
  font-family: var(--font-serif);
  font-size: var(--text-3xl);
  font-weight: 400;
  line-height: var(--leading-tight);
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.section-description {
  margin-top: 0.75rem;
  font-size: var(--text-lg);
  color: var(--text-secondary);
  max-width: 60ch;
}

/* --- Chapter Grid --- */
.chapter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1px;
  background: var(--border-light);
  border: 1px solid var(--border-light);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-md);
}

.chapter-card {
  background: var(--bg-card);
  padding: 1.5rem;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: background var(--transition-fast);
  position: relative;
}

.chapter-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: transparent;
  transition: background var(--transition-fast);
}

.chapter-card:hover {
  background: var(--bg-secondary);
}

.chapter-card:hover::before {
  background: var(--advana-gold);
}

.chapter-card-num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.chapter-card-title {
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--text-primary);
  line-height: var(--leading-snug);
}

.chapter-card-desc {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: var(--leading-relaxed);
  flex: 1;
}

.chapter-card-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: var(--text-xs);
  color: var(--text-muted);
}

.chapter-card-arrow {
  margin-left: auto;
  opacity: 0;
  transform: translateX(-4px);
  transition: opacity var(--transition-fast), transform var(--transition-fast);
  color: var(--text-link);
}

.chapter-card:hover .chapter-card-arrow {
  opacity: 1;
  transform: translateX(0);
}

/* --- Platform Cards --- */
.platform-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1rem;
}

.platform-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 12px;
  padding: 1.5rem;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast);
  box-shadow: var(--shadow-sm);
}

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

.platform-card-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.platform-color-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
}

.platform-card-name {
  font-weight: 700;
  font-size: var(--text-base);
  color: var(--text-primary);
}

.platform-card-desc {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: var(--leading-relaxed);
  flex: 1;
}

.platform-card-tag {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  font-size: var(--text-xs);
  font-weight: 600;
  border-radius: 4px;
  background: var(--bg-secondary);
  color: var(--text-muted);
}

.platform-card.palantir { border-top: 3px solid var(--palantir-blue); }
.platform-card.palantir:hover { border-color: var(--palantir-blue); }
.platform-card.databricks { border-top: 3px solid var(--databricks-red); }
.platform-card.databricks:hover { border-color: var(--databricks-red); }
.platform-card.qlik { border-top: 3px solid var(--qlik-green); }
.platform-card.qlik:hover { border-color: var(--qlik-green); }
.platform-card.jupiter { border-top: 3px solid var(--jupiter-navy); }
.platform-card.jupiter:hover { border-color: var(--jupiter-navy); }
.platform-card.advana { border-top: 3px solid var(--advana-gold); }
.platform-card.advana:hover { border-color: var(--advana-gold); }

/* =========================================================
   CHAPTER PAGE STYLES
   ========================================================= */

.chapter-layout {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 0;
  min-height: calc(100vh - var(--nav-height));
}

.chapter-main {
  grid-column: 1;
  padding: 3rem 2rem 6rem;
  min-width: 0;
  max-width: var(--content-max);
}

.chapter-toc {
  grid-column: 2;
  position: sticky;
  top: calc(var(--nav-height) + 2rem);
  height: fit-content;
  padding: 2rem 1.5rem 2rem 0;
  max-height: calc(100vh - var(--nav-height) - 4rem);
  overflow-y: auto;
}

.toc-label {
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 0.875rem;
  display: block;
}

.toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.125rem;
}

.toc-list a {
  display: block;
  padding: 0.3rem 0.5rem;
  font-size: var(--text-xs);
  color: var(--text-secondary);
  border-left: 2px solid transparent;
  line-height: var(--leading-snug);
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

.toc-list a:hover {
  color: var(--text-primary);
  border-left-color: var(--border-medium);
}

.toc-list a.active {
  color: var(--palantir-blue);
  border-left-color: var(--palantir-blue);
  font-weight: 600;
}

[data-theme="dark"] .toc-list a.active {
  color: var(--advana-gold);
  border-left-color: var(--advana-gold);
}

.toc-list li.toc-h3 a {
  padding-left: 1.25rem;
  font-size: 0.7rem;
}

/* --- Chapter Header --- */
.chapter-header {
  margin-bottom: 1rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-light);
}

.chapter-breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: var(--text-xs);
  color: var(--text-muted);
  margin-bottom: 1.25rem;
}

.chapter-breadcrumb a {
  color: var(--text-muted);
}

.chapter-breadcrumb a:hover {
  color: var(--text-link);
}

.chapter-breadcrumb-sep {
  color: var(--border-medium);
}

.chapter-number {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--advana-gold);
  letter-spacing: 0.04em;
  margin-bottom: 0.625rem;
  display: block;
}

.chapter-title {
  font-family: var(--font-serif);
  font-size: clamp(1.75rem, 3vw, var(--text-4xl));
  font-weight: 400;
  line-height: var(--leading-tight);
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin-bottom: 1.25rem;
}

.chapter-lede {
  font-size: var(--text-lg);
  line-height: var(--leading-relaxed);
  color: var(--text-secondary);
  max-width: 56ch;
  font-style: italic;
}

.chapter-meta-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem;
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border-light);
  font-size: var(--text-xs);
  color: var(--text-muted);
}

.chapter-meta-item {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

a.chapter-meta-link {
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.15s ease;
}

a.chapter-meta-link:hover {
  color: var(--text-link);
}

/* --- Prose Typography --- */
.prose {
  color: var(--text-primary);
}

.prose h2 {
  font-family: var(--font-serif);
  font-size: var(--text-2xl);
  font-weight: 400;
  line-height: var(--leading-tight);
  letter-spacing: -0.015em;
  color: var(--text-primary);
  margin-top: 3rem;
  margin-bottom: 1rem;
  scroll-margin-top: calc(var(--nav-height) + 1rem);
}

.prose h2:first-child {
  margin-top: 0;
}

.prose h3 {
  font-family: var(--font-sans);
  font-size: var(--text-lg);
  font-weight: 700;
  line-height: var(--leading-snug);
  color: var(--text-primary);
  margin-top: 2rem;
  margin-bottom: 0.75rem;
  scroll-margin-top: calc(var(--nav-height) + 1rem);
}

.prose h4 {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: 700;
  color: var(--text-primary);
  margin-top: 1.75rem;
  margin-bottom: 0.625rem;
  scroll-margin-top: calc(var(--nav-height) + 1rem);
}

.prose p {
  font-size: var(--text-base);
  line-height: var(--leading-loose);
  color: var(--text-primary);
  margin-bottom: 1.375rem;
  max-width: 68ch;
}

.prose > p:first-of-type {
  font-size: var(--text-lg);
  color: var(--text-secondary);
}

.prose strong {
  font-weight: 700;
  color: var(--text-primary);
}

.prose em {
  font-style: italic;
}

.prose a {
  color: var(--text-link);
  text-decoration: underline;
  text-decoration-color: rgba(0,59,92,0.3);
  text-underline-offset: 2px;
}

.prose a:hover {
  color: var(--text-link-hover);
  text-decoration-color: var(--text-link-hover);
}

/* Lists */
.prose ul,
.prose ol {
  padding-left: 1.75rem;
  margin-bottom: 1.375rem;
}

.prose li {
  margin-bottom: 0.5rem;
  line-height: var(--leading-relaxed);
  color: var(--text-primary);
}

.prose li::marker {
  color: var(--advana-gold);
}

.prose ul li::before {
  /* handled by list-style */
}

/* Task lists (checkboxes) */
.prose ul.task-list {
  list-style: none;
  padding-left: 0;
}

.prose .task-list li {
  display: flex;
  align-items: flex-start;
  gap: 0.625rem;
  padding: 0.25rem 0;
}

.prose .task-list input[type="checkbox"] {
  margin-top: 0.2rem;
  width: 14px;
  height: 14px;
  accent-color: var(--qlik-green);
  flex-shrink: 0;
}

/* Blockquotes */
.prose blockquote {
  border-left: 3px solid var(--advana-gold);
  padding: 0.75rem 1.25rem;
  margin: 1.75rem 0;
  background: var(--bg-secondary);
  border-radius: 0 8px 8px 0;
}

.prose blockquote p {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  font-style: italic;
  margin-bottom: 0;
  max-width: none;
}

.prose blockquote strong {
  color: var(--text-primary);
  font-style: normal;
}

/* Horizontal rule */
.prose hr {
  border: none;
  border-top: 1px solid var(--border-light);
  margin: 2.5rem 0;
}

/* Tables */
.prose table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
  margin: 1.75rem 0;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.prose th {
  background: var(--palantir-blue);
  color: rgba(255,255,255,0.9);
  font-weight: 600;
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.75rem 1rem;
  text-align: left;
  border: none;
}

.prose td {
  padding: 0.625rem 1rem;
  border-bottom: 1px solid var(--border-light);
  color: var(--text-primary);
  vertical-align: top;
  line-height: var(--leading-relaxed);
}

.prose tr:last-child td {
  border-bottom: none;
}

.prose tr:nth-child(even) td {
  background: var(--bg-secondary);
}

[data-theme="dark"] .prose th {
  background: #0D1A2E;
  color: rgba(255,255,255,0.85);
}

/* Code Inline */
.prose code:not([class]) {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--bg-code);
  /* UX-013: Darkened from #FF3621 to #CC2A17 for WCAG AA contrast (4.5:1+) on #F1F0EC background */
  color: #CC2A17;
  padding: 0.15em 0.4em;
  border-radius: 4px;
  border: 1px solid var(--border-light);
}

[data-theme="dark"] .prose code:not([class]) {
  background: rgba(255,255,255,0.06);
  color: #FF8070;
  border-color: var(--border-light);
}

/* Code Blocks */
.prose pre {
  background: var(--bg-code);
  border: 1px solid var(--border-light);
  border-radius: 10px;
  padding: 1.25rem 1.5rem;
  overflow-x: auto;
  margin: 1.75rem 0;
  position: relative;
}

.prose pre code {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.7;
  background: none;
  border: none;
  padding: 0;
  color: var(--text-primary);
}

.code-block-wrapper {
  position: relative;
  margin: 1.75rem 0;
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 1rem;
  background: var(--palantir-blue);
  border-radius: 10px 10px 0 0;
  border: 1px solid var(--border-light);
  border-bottom: none;
}

.code-block-lang {
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: rgba(255,255,255,0.6);
  font-family: var(--font-mono);
}

.code-copy-btn {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  padding: 0.25rem 0.625rem;
  font-size: var(--text-xs);
  font-weight: 500;
  color: rgba(255,255,255,0.6);
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 4px;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.code-copy-btn:hover {
  color: rgba(255,255,255,0.9);
  background: rgba(255,255,255,0.12);
}

.code-copy-btn.copied {
  color: var(--qlik-green);
  border-color: rgba(0,152,69,0.4);
}

.code-block-wrapper pre {
  margin: 0;
  border-radius: 0 0 10px 10px;
}

/* Mermaid Diagrams */
.mermaid-wrapper {
  margin: 2rem 0;
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 12px;
  overflow-x: auto;
  text-align: center;
  box-shadow: var(--shadow-sm);
}

.mermaid-caption {
  font-size: var(--text-xs);
  color: var(--text-muted);
  text-align: center;
  margin-top: 0.75rem;
  font-style: italic;
}

/* Note / Callout Boxes */
.callout {
  display: flex;
  gap: 0.875rem;
  padding: 1rem 1.25rem;
  border-radius: 8px;
  margin: 1.75rem 0;
  border: 1px solid;
}

.callout-note {
  background: rgba(0,59,92,0.06);
  border-color: rgba(0,59,92,0.2);
}

.callout-warning {
  background: rgba(255,54,33,0.05);
  border-color: rgba(255,54,33,0.2);
}

.callout-tip {
  background: rgba(0,152,69,0.05);
  border-color: rgba(0,152,69,0.2);
}

[data-theme="dark"] .callout-note {
  background: rgba(91,163,201,0.08);
  border-color: rgba(91,163,201,0.2);
}

[data-theme="dark"] .callout-warning {
  background: rgba(255,107,85,0.08);
  border-color: rgba(255,107,85,0.2);
}

[data-theme="dark"] .callout-tip {
  background: rgba(77,201,122,0.08);
  border-color: rgba(77,201,122,0.2);
}

.callout-icon {
  font-size: 1rem;
  flex-shrink: 0;
  margin-top: 0.1rem;
}

.callout-content {
  flex: 1;
  min-width: 0;
}

.callout-content p {
  font-size: var(--text-sm);
  margin-bottom: 0;
  line-height: var(--leading-relaxed);
  max-width: none;
}

/* Failure mode cards */
.failure-card {
  border: 1px solid var(--border-light);
  border-left: 4px solid var(--databricks-red);
  border-radius: 0 8px 8px 0;
  padding: 1.25rem 1.5rem;
  margin: 1.75rem 0;
  background: var(--bg-card);
}

.failure-card h4 {
  color: var(--databricks-red);
  font-size: var(--text-sm);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-top: 0;
  margin-bottom: 0.75rem;
}

/* Chapter Navigation Footer */
.chapter-nav-footer {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-light);
}

.chapter-nav-link {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 1rem 1.25rem;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 10px;
  text-decoration: none;
  transition: all var(--transition-fast);
}

.chapter-nav-link:hover {
  border-color: var(--border-medium);
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
}

.chapter-nav-link.next {
  text-align: right;
}

.chapter-nav-direction {
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.chapter-nav-title {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--text-primary);
}

/* =========================================================
   FOOTER
   ========================================================= */

.site-footer {
  background: var(--palantir-blue);
  color: rgba(255,255,255,0.7);
  padding: 3rem 4rem;
  margin-left: calc(-1 * var(--sidebar-width));
  width: calc(100% + var(--sidebar-width));
  padding-left: calc(var(--sidebar-width) + 4rem);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-brand {
  font-family: var(--font-serif);
  font-size: var(--text-xl);
  font-weight: 400;
  color: rgba(255,255,255,0.9);
  margin-bottom: 0.625rem;
}

.footer-tagline {
  font-size: var(--text-sm);
  line-height: var(--leading-relaxed);
  color: rgba(255,255,255,0.5);
}

.footer-col-title {
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: rgba(255,255,255,0.4);
  margin-bottom: 0.875rem;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-links a {
  font-size: var(--text-sm);
  color: rgba(255,255,255,0.6);
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: rgba(255,255,255,0.9);
}

.footer-bottom {
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255,255,255,0.1);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.footer-copy {
  font-size: var(--text-xs);
  color: rgba(255,255,255,0.35);
}

.footer-platform-dots {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

.footer-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
}

/* =========================================================
   UTILITY CLASSES
   ========================================================= */

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* UX-011: Skip-to-content link — visible on keyboard focus */
.skip-to-content:focus {
  position: fixed;
  top: 0.75rem;
  left: 50%;
  transform: translateX(-50%);
  width: auto;
  height: auto;
  padding: 0.625rem 1.25rem;
  clip: auto;
  overflow: visible;
  white-space: nowrap;
  background: var(--advana-gold);
  color: #1A1A1A;
  font-size: var(--text-sm);
  font-weight: 700;
  border-radius: 8px;
  z-index: 9999;
  text-decoration: none;
  box-shadow: var(--shadow-md);
}

.text-center { text-align: center; }
.font-mono { font-family: var(--font-mono); }

/* =========================================================
   RESPONSIVE DESIGN
   ========================================================= */

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

  .chapter-toc {
    display: none;
  }

  .chapter-main {
    max-width: var(--content-max);
  }
}

@media (max-width: 900px) {
  :root {
    --sidebar-width: 0px;
  }

  .sidebar {
    transform: translateX(-260px);
    width: 260px;
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .sidebar-overlay.active {
    display: block;
  }

  .main-content {
    margin-left: 0;
  }

  .mobile-menu-btn {
    display: flex;
  }

  .site-footer {
    margin-left: 0;
    width: 100%;
    padding-left: 4rem;
  }

  .hero {
    padding: 3rem 1.5rem 2.5rem;
  }

  .section {
    padding: 2.5rem 1.5rem;
  }

  .platform-strip {
    padding: 1rem 1.5rem;
  }

  .hero-stats {
    gap: 1.25rem;
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }

  .chapter-layout {
    grid-template-columns: 1fr;
  }

  .chapter-main {
    padding: 2rem 1.5rem 4rem;
  }
}

@media (max-width: 600px) {
  .hero-stats {
    flex-direction: column;
    gap: 1rem;
  }

  .nav-links {
    display: none;
  }

  .chapter-grid {
    grid-template-columns: 1fr;
  }

  .platform-grid {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr;
  }

  .chapter-nav-footer {
    grid-template-columns: 1fr;
  }

  .site-footer {
    padding: 2rem 1.5rem;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}

/* Print */
@media print {
  .site-nav, .sidebar, .chapter-toc, .chapter-nav-footer {
    display: none !important;
  }

  .main-content {
    margin: 0 !important;
  }

  .chapter-main {
    padding: 0 !important;
  }
}

/* ======================================================
   EXERCISES CALLOUT
   ====================================================== */
.exercises-callout {
  margin: 3rem 0 2rem;
  padding: 1.5rem 2rem;
  background: var(--bg-secondary);
  border-left: 4px solid var(--advana-gold, #C5A572);
  border-radius: 0 8px 8px 0;
}

.exercises-callout h2 {
  font-family: var(--font-serif, Georgia, 'Times New Roman', serif);
  font-size: 1.25rem;
  margin: 0 0 0.5rem;
  color: var(--text-primary);
}

.exercises-callout p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin: 0 0 1rem;
  line-height: 1.6;
}

.exercises-callout .btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  font-size: 0.875rem;
  padding: 0.5rem 1rem;
  text-decoration: none;
}

/* ======================================================
   CHAPTER REPO LINK
   ====================================================== */
.chapter-repo-link {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-size: var(--text-xs, 0.75rem);
  color: var(--text-muted);
  text-decoration: none;
  margin-top: 0.5rem;
  transition: color 0.15s ease;
}

.chapter-repo-link:hover {
  color: var(--text-link);
}

/* ======================================================
   TOOLKIT SECTION (Homepage)
   ====================================================== */
.toolkit-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.25rem;
  margin-top: 2rem;
}

.toolkit-card {
  display: flex;
  flex-direction: column;
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 12px;
  text-decoration: none;
  color: var(--text-primary);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.toolkit-card:hover {
  border-color: var(--border-accent, #C5A572);
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.toolkit-card-icon {
  font-size: 1.75rem;
  margin-bottom: 0.75rem;
}

.toolkit-card-title {
  font-weight: 600;
  font-size: 1rem;
  margin-bottom: 0.375rem;
}

.toolkit-card-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.toolkit-card-stat {
  margin-top: auto;
  padding-top: 0.75rem;
  font-size: var(--text-xs, 0.75rem);
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

/* ======================================================
   SECURITY MODULE CARDS
   ====================================================== */
.security-module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.25rem;
  margin: 2rem 0;
}

.security-module-card {
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 12px;
  border-top: 3px solid var(--palantir-blue, #1B2A4A);
}

.security-module-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 0 0 0.5rem;
  color: var(--text-primary);
}

.security-module-card p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0 0 0.75rem;
}

.security-module-card .module-stat {
  font-size: var(--text-xs, 0.75rem);
  color: var(--text-muted);
  font-weight: 600;
}

.security-stats-bar {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 1rem;
  padding: 1.5rem;
  background: var(--bg-secondary);
  border-radius: 12px;
  margin: 2rem 0;
  text-align: center;
}

.security-stat-item .security-stat-value {
  display: block;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

.security-stat-item .security-stat-label {
  font-size: var(--text-xs, 0.75rem);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.benchmark-callout {
  padding: 1.25rem 1.5rem;
  background: var(--bg-secondary);
  border-left: 4px solid var(--qlik-green, #009845);
  border-radius: 0 8px 8px 0;
  margin: 2rem 0;
}

.benchmark-callout p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.6;
}

/* ======================================================
   DOCKER SERVICE CARDS
   ====================================================== */
.docker-service-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin: 2rem 0;
}

.docker-service-card {
  padding: 1.25rem;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 10px;
  text-align: center;
}

.docker-service-card .service-name {
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 0.25rem;
}

.docker-service-card .service-desc {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

.docker-service-card .service-port {
  font-size: var(--text-xs, 0.75rem);
  color: var(--text-muted);
  font-family: var(--font-mono, 'SF Mono', 'Fira Code', monospace);
}

/* ======================================================
   PLATFORM HERO (consolidated from inline styles)
   ====================================================== */
.platform-hero {
  background: var(--platform-color, #1B2A4A);
  color: #fff;
  padding: clamp(2rem, 5vw, 4rem) clamp(1.5rem, 4vw, 3rem);
  position: relative;
  overflow: hidden;
}

.platform-hero::before {
  content: '';
  position: absolute;
  right: -60px;
  top: -60px;
  width: 280px;
  height: 280px;
  border-radius: 50%;
  background: rgba(255,255,255,0.04);
  pointer-events: none;
}

.platform-eyebrow {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: var(--text-xs, 0.75rem);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: rgba(255,255,255,0.7);
  margin-bottom: 0.75rem;
}

.platform-dot-large {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #fff;
  display: inline-block;
}

.platform-hero-title {
  font-family: var(--font-serif, Georgia, 'Times New Roman', serif);
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  line-height: 1.15;
  margin: 0 0 1rem;
}

.platform-hero-desc {
  font-size: 1.125rem;
  line-height: 1.65;
  color: rgba(255,255,255,0.75);
  max-width: 56ch;
  margin: 0;
}

.platform-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.25rem;
}

.platform-tag-pill {
  padding: 0.25rem 0.75rem;
  font-size: var(--text-xs, 0.75rem);
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: 999px;
  background: rgba(255,255,255,0.08);
  color: rgba(255,255,255,0.9);
}

.platform-facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  background: var(--bg-card);
  border-bottom: 1px solid var(--border-light);
}

.platform-fact {
  padding: 1rem 1.25rem;
  border-right: 1px solid var(--border-light);
}

.platform-fact:last-child {
  border-right: none;
}

.platform-fact-label,
.platform-fact dt {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 0.25rem;
  font-weight: 500;
}

.platform-fact-value,
.platform-fact dd {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0;
}

/* GitHub nav icon */
.nav-github svg {
  fill: currentColor;
}

@media (max-width: 900px) {
  .platform-facts {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 600px) {
  .platform-facts {
    grid-template-columns: 1fr;
  }
  .toolkit-grid {
    grid-template-columns: 1fr;
  }
  .security-module-grid {
    grid-template-columns: 1fr;
  }
}

/* =========================================================
   AGENT-READY SECTION (Homepage)
   ========================================================= */

.agent-section-inner {
  display: grid;
  grid-template-columns: 1fr 1.4fr;
  gap: 3rem;
  align-items: start;
}

.agent-section-desc {
  font-size: var(--text-lg);
  line-height: var(--leading-relaxed);
  color: var(--text-secondary);
  max-width: 48ch;
  margin: 1rem 0 1.75rem;
}

.agent-section-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.btn-agents-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6875rem 1.375rem;
  font-size: var(--text-sm);
  font-weight: 600;
  background: var(--palantir-blue);
  color: #FFFFFF;
  border: none;
  border-radius: 8px;
  text-decoration: none;
  transition: background var(--transition-fast), transform var(--transition-fast);
}

.btn-agents-primary:hover {
  background: #253D6E;
  color: #FFFFFF;
  transform: translateY(-1px);
}

[data-theme="dark"] .btn-agents-primary {
  background: var(--advana-gold);
  color: #0F1117;
}

[data-theme="dark"] .btn-agents-primary:hover {
  background: #D4B483;
  color: #0F1117;
}

.btn-agents-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6875rem 1.375rem;
  font-size: var(--text-sm);
  font-weight: 600;
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-medium);
  border-radius: 8px;
  text-decoration: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.btn-agents-secondary:hover {
  border-color: var(--border-accent);
  box-shadow: var(--shadow-sm);
  color: var(--text-primary);
}

/* Agent command cards (homepage) */

.agent-commands-grid {
  display: flex;
  flex-direction: column;
  gap: 1px;
  background: var(--border-light);
  border: 1px solid var(--border-light);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-md);
}

.agent-command-card {
  background: var(--bg-card);
  padding: 1.5rem;
  border-left: 3px solid transparent;
  transition: background var(--transition-fast), border-color var(--transition-fast);
}

.agent-command-card:hover {
  background: var(--bg-secondary);
  border-left-color: var(--advana-gold);
}

.agent-command-header {
  margin-bottom: 0.625rem;
}

.agent-command-name {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--advana-gold);
  background: var(--bg-code);
  padding: 0.25rem 0.625rem;
  border-radius: 4px;
  letter-spacing: 0.02em;
}

[data-theme="dark"] .agent-command-name {
  background: var(--bg-secondary);
}

.agent-command-desc {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0 0 0.875rem;
}

.agent-command-tools {
  display: flex;
  flex-wrap: wrap;
  gap: 0.375rem;
}

.agent-tool-tag {
  display: inline-block;
  padding: 0.15rem 0.5rem;
  font-size: var(--text-xs);
  font-weight: 600;
  font-family: var(--font-mono);
  border-radius: 3px;
  background: var(--bg-secondary);
  color: var(--text-muted);
  border: 1px solid var(--border-light);
}

[data-theme="dark"] .agent-tool-tag {
  background: var(--bg-code);
}

/* =========================================================
   AGENTS PAGE — Tool Support Grid
   ========================================================= */

.agent-tool-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin: 1.75rem 0;
}

.agent-tool-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 12px;
  padding: 1.25rem 1.5rem;
  border-top: 3px solid var(--palantir-blue);
}

[data-theme="dark"] .agent-tool-card {
  border-top-color: var(--advana-gold);
}

.agent-tool-card-name {
  font-weight: 700;
  font-size: var(--text-base);
  color: var(--text-primary);
  margin-bottom: 0.875rem;
}

.agent-tool-card-detail {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: var(--leading-relaxed);
  margin-bottom: 0.5rem;
}

.agent-tool-card-file {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--text-muted);
  background: var(--bg-code);
  padding: 0.15rem 0.4rem;
  border-radius: 3px;
}

/* =========================================================
   AGENT SECTIONS — Responsive
   ========================================================= */

@media (max-width: 900px) {
  .agent-section-inner {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .agent-section-desc {
    max-width: none;
  }

  .agent-tool-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 600px) {
  .agent-section-actions {
    flex-direction: column;
  }
}