:root {
  --bg-parchment: #FAF7F2;
  --bg-surface: #FFFFFF;
  --bg-subtle: #F2ECE4;
  --bg-card-shell: #F4EFEA;
  --bg-card-core: #FFFFFF;
  
  --ink-primary: #12110F;
  --ink-secondary: #4A463F;
  --ink-tertiary: #7D766C;
  --ink-quaternary: #AEA79B;
  
  --gold-foil: #C59B3F;
  --gold-light: #E8C87A;
  --gold-glow: rgba(197, 155, 63, 0.16);
  --gold-deep: #87651D;
  --gold-border: rgba(197, 155, 63, 0.35);
  
  --border-hairline: rgba(21, 19, 15, 0.08);
  --border-delicate: #E7DFD3;
  --border-strong: #D1C5B5;
  
  --cat-safety: #BA382B;
  --cat-safety-bg: #FDF2F0;
  --cat-network: #0D7D72;
  --cat-network-bg: #EBF8F6;
  --cat-dev: #1D58D8;
  --cat-dev-bg: #EEF4FF;
  --cat-ai: #6D28D9;
  --cat-ai-bg: #F5F2FF;
  
  --serif-title: 'Playfair Display', 'Newsreader', Georgia, serif;
  --serif-italic: 'Newsreader', Georgia, serif;
  --sans-ui: 'Plus Jakarta Sans', -apple-system, sans-serif;
  --mono-code: 'JetBrains Mono', monospace;
  
  --ease-luxury: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
  
  --shadow-ambient: 0 30px 90px -20px rgba(18, 17, 15, 0.12), 0 10px 30px -10px rgba(18, 17, 15, 0.06);
  --shadow-floating: 0 24px 64px -12px rgba(18, 17, 15, 0.15), 0 4px 16px rgba(18, 17, 15, 0.04);
  --shadow-double-bezel: inset 0 1px 1px rgba(255, 255, 255, 0.8), 0 12px 36px -8px rgba(18, 17, 15, 0.08);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  background-color: var(--bg-parchment);
  color: var(--ink-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--sans-ui);
  line-height: 1.6;
  background: 
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(197, 155, 63, 0.08) 0%, transparent 100%),
    radial-gradient(circle at 10% 30%, rgba(242, 236, 228, 0.8) 0%, transparent 60%),
    var(--bg-parchment);
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

/* Subtle physical paper grain */
.paper-grain {
  position: fixed;
  inset: 0;
  background-image: radial-gradient(rgba(18, 17, 15, 0.035) 1px, transparent 0);
  background-size: 20px 20px;
  pointer-events: none;
  z-index: 9999;
}

.container {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 clamp(1.25rem, 5vw, 3rem);
}

/* ==========================================================================
   1. Floating Island Masthead (Luxury Nav)
   ========================================================================== */
.nav-island-wrapper {
  position: sticky;
  top: 1.25rem;
  z-index: 1000;
  display: flex;
  justify-content: center;
  padding: 0 1rem;
  pointer-events: none;
}

.nav-island {
  pointer-events: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2.5rem;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  padding: 0.5rem 0.6rem 0.5rem 1.4rem;
  border-radius: 9999px;
  border: 1px solid rgba(21, 19, 15, 0.09);
  box-shadow: 0 12px 32px -8px rgba(18, 17, 15, 0.12), 0 2px 6px rgba(18, 17, 15, 0.04);
  max-width: 960px;
  width: 100%;
  transition: all 0.3s var(--ease-luxury);
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--ink-primary);
}

.wordmark-sigil {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  border: 1.5px solid var(--gold-foil);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  background: #FFF;
}

.wordmark-sigil::after {
  content: "";
  width: 7px;
  height: 7px;
  background: var(--gold-foil);
  border-radius: 50%;
}

.wordmark-text {
  font-family: var(--serif-title);
  font-size: 1.25rem;
  font-weight: 500;
  letter-spacing: -0.02em;
}

.wordmark-imprint {
  font-size: 0.65rem;
  font-family: var(--mono-code);
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--gold-deep);
  background: var(--gold-glow);
  padding: 2px 7px;
  border-radius: 999px;
  border: 1px solid var(--gold-border);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.75rem;
}

.nav-links a {
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--ink-secondary);
  transition: color 0.2s var(--ease-luxury);
}

.nav-links a:hover {
  color: var(--ink-primary);
}

/* Button-in-Button Trailing Pill */
.btn-nav-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  background: var(--ink-primary);
  color: #FFFFFF !important;
  padding: 0.4rem 0.45rem 0.4rem 1.15rem;
  border-radius: 9999px;
  font-size: 0.82rem !important;
  font-weight: 500;
  text-decoration: none;
  transition: all 0.25s var(--ease-luxury);
}

.btn-nav-pill:hover {
  background: #000000;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.btn-icon-bubble {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.18);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  transition: transform 0.25s var(--ease-luxury);
}

.btn-nav-pill:hover .btn-icon-bubble {
  transform: translateX(2px);
  background: rgba(255, 255, 255, 0.28);
}

/* ==========================================================================
   2. Hero Section & Atmospheric Lighting
   ========================================================================== */
.hero {
  padding: clamp(3rem, 6vw, 5rem) 0 clamp(4rem, 8vw, 6.5rem);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: clamp(2.5rem, 5vw, 5rem);
  align-items: center;
}

.hero-copy {
  display: flex;
  flex-direction: column;
}

.eyebrow-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--mono-code);
  font-size: 0.74rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--gold-deep);
  background: rgba(197, 155, 63, 0.09);
  padding: 4px 12px;
  border-radius: 999px;
  border: 1px solid var(--gold-border);
  width: fit-content;
  margin-bottom: 1.5rem;
}

.eyebrow-pill .pulsing-orb {
  width: 6px;
  height: 6px;
  background: var(--gold-foil);
  border-radius: 50%;
  box-shadow: 0 0 0 3px var(--gold-glow);
}

.hero-title {
  font-family: var(--serif-title);
  font-size: clamp(2.6rem, 5.2vw, 4.4rem);
  font-weight: 400;
  line-height: 1.04;
  letter-spacing: -0.028em;
  color: var(--ink-primary);
  margin-bottom: 1.6rem;
  text-wrap: balance;
}

.hero-title em {
  font-family: var(--serif-italic);
  font-style: italic;
  font-weight: 400;
  color: var(--gold-deep);
  background: linear-gradient(135deg, var(--gold-deep) 0%, var(--gold-foil) 70%, #9C7726 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-lead {
  font-size: clamp(1.05rem, 1.8vw, 1.22rem);
  line-height: 1.68;
  color: var(--ink-secondary);
  margin-bottom: 1.75rem;
  max-width: 46ch;
}

/* Double-Bezel Pullquote */
.quote-bezel-shell {
  background: rgba(197, 155, 63, 0.06);
  border: 1px solid var(--gold-border);
  border-radius: 12px;
  padding: 3px;
  margin-bottom: 2.25rem;
  max-width: 48ch;
}

.quote-bezel-core {
  background: #FFFFFF;
  border-radius: 9px;
  padding: 1rem 1.25rem;
  border-left: 3px solid var(--gold-foil);
}

.quote-bezel-core p {
  font-family: var(--serif-italic);
  font-size: 1.08rem;
  font-style: italic;
  line-height: 1.5;
  color: var(--ink-primary);
}

/* Island CTA Buttons */
.hero-ctas {
  display: flex;
  align-items: center;
  gap: 1.15rem;
  flex-wrap: wrap;
}

.btn-island-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  background: var(--ink-primary);
  color: #FFFFFF;
  padding: 0.55rem 0.65rem 0.55rem 1.65rem;
  border-radius: 9999px;
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  box-shadow: 0 10px 24px -4px rgba(18, 17, 15, 0.25);
  transition: all 0.25s var(--ease-luxury);
}

.btn-island-primary:hover {
  background: #000000;
  transform: translateY(-2px);
  box-shadow: 0 16px 36px -6px rgba(18, 17, 15, 0.35);
}

.btn-bubble-arrow {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  transition: transform 0.25s var(--ease-luxury), background 0.25s;
}

.btn-island-primary:hover .btn-bubble-arrow {
  transform: translateX(3px) scale(1.05);
  background: rgba(255, 255, 255, 0.3);
}

.btn-island-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(255, 255, 255, 0.9);
  color: var(--ink-primary);
  padding: 0.85rem 1.6rem;
  border-radius: 9999px;
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  border: 1px solid var(--border-delicate);
  box-shadow: 0 2px 8px rgba(18, 17, 15, 0.04);
  transition: all 0.25s var(--ease-luxury);
}

.btn-island-secondary:hover {
  background: #FFFFFF;
  border-color: var(--gold-foil);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px -4px rgba(18, 17, 15, 0.08);
}

/* ==========================================================================
   3. Stacked Physical Card Deck (Museum / Exhibition Tier)
   ========================================================================== */
.deck-stage-shell {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

/* Tab Switcher Bar */
.deck-tabs-island {
  display: flex;
  gap: 0.4rem;
  background: rgba(235, 227, 216, 0.5);
  padding: 5px;
  border-radius: 9999px;
  border: 1px solid var(--border-delicate);
  overflow-x: auto;
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.03);
}

.deck-tab-btn {
  flex: 1;
  padding: 0.55rem 0.95rem;
  font-size: 0.8rem;
  font-weight: 600;
  font-family: var(--mono-code);
  text-align: center;
  color: var(--ink-tertiary);
  background: transparent;
  border: none;
  border-radius: 9999px;
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.25s var(--ease-luxury);
}

.deck-tab-btn:hover {
  color: var(--ink-primary);
}

.deck-tab-btn.active {
  background: #FFFFFF;
  color: var(--ink-primary);
  box-shadow: 0 3px 10px rgba(0, 0, 0, 0.08);
}

/* Stacked Physical Under-Cards (Z-Axis Depth) */
.cards-perspective-wrap {
  position: relative;
  perspective: 1400px;
}

.under-card-layer {
  position: absolute;
  inset: 0;
  border-radius: 20px;
  border: 1px solid var(--border-delicate);
  background: #F4EFEA;
  pointer-events: none;
  transition: all 0.4s var(--ease-luxury);
}

.under-card-2 {
  transform: translateY(14px) scale(0.96) rotate(-1.5deg);
  opacity: 0.55;
  box-shadow: 0 10px 30px rgba(0,0,0,0.04);
}

.under-card-1 {
  transform: translateY(7px) scale(0.98) rotate(1deg);
  opacity: 0.8;
  background: #FAF7F2;
  box-shadow: 0 15px 40px rgba(0,0,0,0.06);
}

/* Double-Bezel Card Container */
.card-bezel-outer {
  position: relative;
  background: rgba(255, 255, 255, 0.7);
  padding: 6px;
  border-radius: 22px;
  border: 1px solid rgba(21, 19, 15, 0.08);
  box-shadow: var(--shadow-ambient);
  transition: transform 0.35s var(--ease-luxury), box-shadow 0.35s ease;
}

.card-bezel-inner {
  background: #FFFFFF;
  border-radius: 17px;
  border: 1px solid var(--border-delicate);
  overflow: hidden;
  box-shadow: inset 0 1px 1px rgba(255, 255, 255, 0.9);
}

/* Card Header Foil Banner */
.card-header-bar {
  padding: 1.15rem 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: relative;
  transition: background 0.3s ease;
}

.theme-safety .card-header-bar { background: var(--cat-safety); color: #FFF; }
.theme-network .card-header-bar { background: var(--cat-network); color: #FFF; }
.theme-dev .card-header-bar { background: var(--cat-dev); color: #FFF; }
.theme-ai .card-header-bar { background: var(--cat-ai); color: #FFF; }

.card-term-heading {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.015em;
}

.card-chapter-badge {
  font-family: var(--mono-code);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  padding: 3px 9px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.22);
  text-transform: uppercase;
}

/* Card Content Body */
.card-main-body {
  padding: 1.6rem 1.6rem 1.35rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.card-plain-sentence {
  font-size: 1.08rem;
  line-height: 1.52;
  color: var(--ink-primary);
  font-weight: 450;
}

.gilded-hairline {
  height: 2px;
  width: 80px;
  background: linear-gradient(90deg, var(--gold-foil) 0%, transparent 100%);
}

/* Vector Diagram Stage */
.diagram-canvas-enclosure {
  background: var(--bg-parchment);
  border-radius: 12px;
  border: 1px solid var(--border-delicate);
  padding: 1.25rem;
  min-height: 175px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.card-analogy-row {
  padding-top: 0.6rem;
  border-top: 1px solid var(--border-delicate);
}

.analogy-eyebrow {
  font-family: var(--mono-code);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--gold-deep);
  margin-bottom: 0.2rem;
}

.analogy-quote {
  font-family: var(--serif-italic);
  font-style: italic;
  font-size: 1.05rem;
  color: var(--ink-primary);
  line-height: 1.45;
}

.card-example-row {
  padding-top: 0.6rem;
  border-top: 1px dashed var(--border-delicate);
}

.example-eyebrow {
  font-family: var(--mono-code);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-tertiary);
  margin-bottom: 0.2rem;
}

.example-body {
  font-size: 0.92rem;
  color: var(--ink-secondary);
  line-height: 1.5;
}

.deck-footer-note {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--ink-tertiary);
  padding: 0 0.5rem;
}

.live-pulse-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--mono-code);
  font-size: 0.72rem;
  color: var(--gold-deep);
}

.live-pulse-badge::before {
  content: "";
  width: 7px;
  height: 7px;
  background: var(--gold-foil);
  border-radius: 50%;
  animation: pulseGold 2s infinite ease-in-out;
}

@keyframes pulseGold {
  0%, 100% { opacity: 0.4; transform: scale(0.9); }
  50% { opacity: 1; transform: scale(1.2); }
}

/* ==========================================================================
   4. NEW FEATURE: Interactive "Peek Inside the 100 Cards" Showcase
   ========================================================================== */
.cards-sampler-section {
  padding: clamp(4rem, 7vw, 6rem) 0;
  background: #FFFFFF;
  border-top: 1px solid var(--border-delicate);
  border-bottom: 1px solid var(--border-delicate);
}

.sampler-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-bottom: 2.5rem;
  flex-wrap: wrap;
  gap: 1.5rem;
}

.sampler-chips-shelf {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-bottom: 2rem;
}

.sample-word-pill {
  font-family: var(--mono-code);
  font-size: 0.84rem;
  padding: 0.45rem 1rem;
  border-radius: 999px;
  background: var(--bg-parchment);
  color: var(--ink-primary);
  border: 1px solid var(--border-delicate);
  cursor: pointer;
  transition: all 0.2s var(--ease-luxury);
  user-select: none;
}

.sample-word-pill:hover {
  border-color: var(--gold-foil);
  background: #FFFFFF;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(18, 17, 15, 0.06);
}

.sample-word-pill.active {
  background: var(--ink-primary);
  color: #FFFFFF;
  border-color: var(--ink-primary);
  box-shadow: 0 4px 14px rgba(18, 17, 15, 0.2);
}

/* Live Word Quick Inspector Box */
.inspector-shell {
  background: var(--bg-parchment);
  border: 1px solid var(--border-delicate);
  border-radius: 18px;
  padding: 2rem clamp(1.5rem, 4vw, 3rem);
  box-shadow: inset 0 2px 4px rgba(0,0,0,0.02);
  display: grid;
  grid-template-columns: 1fr 1.6fr;
  gap: clamp(2rem, 4vw, 3.5rem);
  align-items: center;
}

.inspector-word-col h3 {
  font-family: var(--serif-title);
  font-size: 2.2rem;
  font-weight: 500;
  margin-bottom: 0.5rem;
  color: var(--ink-primary);
}

.inspector-meta {
  font-family: var(--mono-code);
  font-size: 0.78rem;
  color: var(--gold-deep);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 1.25rem;
}

.inspector-analogy {
  font-family: var(--serif-italic);
  font-style: italic;
  font-size: 1.15rem;
  line-height: 1.5;
  color: var(--ink-primary);
  border-left: 2px solid var(--gold-foil);
  padding-left: 1rem;
}

.inspector-explanation-col p {
  font-size: 1.05rem;
  line-height: 1.65;
  color: var(--ink-secondary);
  margin-bottom: 1.5rem;
}

.inspector-download-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  font-size: 0.92rem;
  color: var(--ink-primary);
  text-decoration: none;
  border-bottom: 1.5px solid var(--gold-foil);
  padding-bottom: 2px;
  transition: all 0.2s ease;
}

.inspector-download-link:hover {
  color: var(--gold-deep);
  border-color: var(--gold-deep);
  transform: translateX(3px);
}

/* ==========================================================================
   5. The 5-Layer System Section (Double-Bezel Masonry)
   ========================================================================== */
.philosophy {
  padding: clamp(5rem, 9vw, 7.5rem) 0;
}

.section-eyebrow {
  font-family: var(--mono-code);
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  color: var(--gold-deep);
  margin-bottom: 0.75rem;
}

.section-h2 {
  font-family: var(--serif-title);
  font-size: clamp(2.2rem, 4vw, 3.2rem);
  font-weight: 400;
  letter-spacing: -0.02em;
  line-height: 1.12;
  color: var(--ink-primary);
  margin-bottom: 1.25rem;
}

.section-p {
  font-size: 1.12rem;
  color: var(--ink-secondary);
  max-width: 54ch;
  line-height: 1.65;
  margin-bottom: 3.5rem;
}

.layers-cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
}

/* Double-bezel feature card */
.bezel-feature-card {
  background: rgba(235, 227, 216, 0.4);
  padding: 5px;
  border-radius: 18px;
  border: 1px solid var(--border-delicate);
  transition: all 0.3s var(--ease-luxury);
}

.bezel-feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 16px 36px -8px rgba(18, 17, 15, 0.08);
  border-color: var(--gold-foil);
}

.bezel-feature-inner {
  background: #FFFFFF;
  border-radius: 14px;
  padding: 1.75rem 1.4rem;
  height: 100%;
  display: flex;
  flex-direction: column;
  border: 1px solid rgba(255, 255, 255, 0.9);
}

.bezel-feature-num {
  font-family: var(--mono-code);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--gold-deep);
  margin-bottom: 1rem;
}

.bezel-feature-title {
  font-family: var(--serif-title);
  font-size: 1.35rem;
  font-weight: 500;
  color: var(--ink-primary);
  margin-bottom: 0.6rem;
  line-height: 1.25;
}

.bezel-feature-text {
  font-size: 0.94rem;
  color: var(--ink-secondary);
  line-height: 1.6;
}

/* ==========================================================================
   6. Luxury Book Catalogue (Physical Book Jackets)
   ========================================================================== */
.catalogue {
  padding: clamp(5rem, 8vw, 7rem) 0;
  background: radial-gradient(circle at 50% 10%, #FFFFFF 0%, var(--bg-parchment) 70%);
}

.catalogue-divider-bar {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  border-bottom: 1px solid var(--ink-primary);
  padding-bottom: 1.5rem;
  margin-bottom: 3.5rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.catalogue-shelf-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2.5rem;
}

/* Double-bezel Book Card */
.book-jacket-shell {
  background: rgba(244, 239, 234, 0.6);
  padding: 6px;
  border-radius: 22px;
  border: 1px solid var(--border-delicate);
  box-shadow: 0 4px 20px rgba(18, 17, 15, 0.04);
  transition: all 0.35s var(--ease-luxury);
  display: flex;
  flex-direction: column;
}

.book-jacket-shell:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 60px -12px rgba(18, 17, 15, 0.14);
  border-color: var(--border-strong);
}

.book-jacket-shell.featured-edition {
  background: rgba(197, 155, 63, 0.08);
  border-color: var(--gold-foil);
}

.book-jacket-inner {
  background: #FFFFFF;
  border-radius: 17px;
  padding: 2.25rem 2rem;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  border: 1px solid var(--border-delicate);
}

.book-top-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 1.25rem;
}

.book-badge-chip {
  font-family: var(--mono-code);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--gold-deep);
  background: var(--gold-glow);
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid var(--gold-border);
}

.book-badge-chip.featured {
  background: var(--gold-foil);
  color: #FFFFFF;
  border-color: var(--gold-foil);
}

.book-price-display {
  font-family: var(--mono-code);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--ink-primary);
}

.book-cloth-spine {
  height: 6px;
  border-radius: 999px;
  margin-bottom: 1.5rem;
  background: linear-gradient(90deg, var(--gold-foil) 0%, #F5E2B3 50%, var(--gold-foil) 100%);
}

.book-cloth-spine.spine-dev { background: var(--cat-dev); }
.book-cloth-spine.spine-dark { background: var(--ink-primary); }

.book-main-title {
  font-family: var(--serif-title);
  font-size: 1.65rem;
  line-height: 1.2;
  font-weight: 500;
  color: var(--ink-primary);
  margin-bottom: 0.4rem;
}

.book-sub-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--cat-dev);
  margin-bottom: 1.15rem;
}

.book-description-text {
  font-size: 0.96rem;
  color: var(--ink-secondary);
  line-height: 1.62;
  margin-bottom: 1.75rem;
}

.book-spec-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
}

.spec-chip {
  font-family: var(--mono-code);
  font-size: 0.72rem;
  color: var(--ink-secondary);
  background: var(--bg-parchment);
  border: 1px solid var(--border-delicate);
  padding: 3px 9px;
  border-radius: 6px;
}

.book-checkout-bar {
  border-top: 1px solid var(--border-delicate);
  padding-top: 1.35rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.btn-book-action {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  font-size: 0.94rem;
  font-weight: 600;
  color: var(--ink-primary);
  border-bottom: 2px solid var(--gold-foil);
  padding-bottom: 2px;
  transition: all 0.2s ease;
}

.btn-book-action:hover {
  color: var(--gold-deep);
  border-bottom-color: var(--gold-deep);
  transform: translateX(3px);
}

.btn-book-action.gold-prominent {
  color: var(--gold-deep);
  font-size: 1.02rem;
}

.delivery-note {
  font-size: 0.78rem;
  color: var(--ink-tertiary);
}

/* ==========================================================================
   7. Colophon & Press Heritage
   ========================================================================== */
.colophon-section {
  background: #FFFFFF;
  border-top: 1px solid var(--border-delicate);
  border-bottom: 1px solid var(--border-delicate);
  padding: clamp(5rem, 8vw, 7rem) 0;
}

.colophon-columns {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(290px, 1fr));
  gap: 3.5rem;
}

.colophon-block h3 {
  font-family: var(--serif-title);
  font-size: 1.45rem;
  font-weight: 500;
  color: var(--ink-primary);
  margin-bottom: 1.15rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.colophon-block h3::before {
  content: "";
  width: 7px;
  height: 7px;
  background: var(--gold-foil);
  border-radius: 50%;
}

.colophon-block p {
  font-size: 1rem;
  color: var(--ink-secondary);
  line-height: 1.68;
  margin-bottom: 1rem;
}

.colophon-block a {
  color: var(--ink-primary);
  text-decoration: none;
  border-bottom: 1px solid var(--gold-foil);
  transition: all 0.2s ease;
}

.colophon-block a:hover {
  color: var(--gold-deep);
  border-color: var(--gold-deep);
}

/* ==========================================================================
   8. Footer
   ========================================================================== */
footer {
  padding: 3.5rem 0 4.5rem;
  font-size: 0.88rem;
  color: var(--ink-tertiary);
}

.footer-stack {
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
}

.footer-links-row {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
}

.footer-links-row a {
  color: var(--ink-secondary);
  text-decoration: none;
  transition: color 0.2s ease;
}

.footer-links-row a:hover {
  color: var(--gold-deep);
}

.footer-legal-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
  border-top: 1px solid var(--border-delicate);
  padding-top: 1.75rem;
  font-size: 0.82rem;
}

/* Responsive */
@media (max-width: 960px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 3.5rem;
  }
  
  .inspector-shell {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
  
  .nav-island {
    gap: 1rem;
  }
  
  .nav-links {
    display: none;
  }
}

/* ==========================================================================
   THEME 2: OBSIDIAN & GOLD (Dark Luxury / Tech Bible)
   ========================================================================== */
[data-theme="obsidian"] {
  --bg-parchment: #08080A;
  --bg-surface: #101014;
  --bg-subtle: #18181F;
  --bg-card-shell: #141418;
  --bg-card-core: #0D0D11;
  
  --ink-primary: #F8F8F8;
  --ink-secondary: #B4B0A8;
  --ink-tertiary: #7D786E;
  --ink-quaternary: #4A463F;
  
  --gold-foil: #E5A93C;
  --gold-light: #FCD34D;
  --gold-glow: rgba(229, 169, 60, 0.28);
  --gold-deep: #FBBF24;
  --gold-border: rgba(229, 169, 60, 0.4);
  
  --border-hairline: rgba(255, 255, 255, 0.07);
  --border-delicate: #22222A;
  --border-strong: #33333E;
  
  --shadow-ambient: 0 30px 90px -20px rgba(0, 0, 0, 0.8), 0 0 40px rgba(229, 169, 60, 0.08);
}

[data-theme="obsidian"] body {
  background: 
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(229, 169, 60, 0.15) 0%, transparent 100%),
    radial-gradient(circle at 10% 30%, rgba(20, 20, 26, 0.8) 0%, transparent 60%),
    #08080A;
}

[data-theme="obsidian"] .paper-grain {
  background-image: radial-gradient(rgba(255, 255, 255, 0.04) 1px, transparent 0);
}

[data-theme="obsidian"] .nav-island {
  background: rgba(14, 14, 18, 0.88);
  border-color: rgba(255, 255, 255, 0.12);
  box-shadow: 0 12px 32px -8px rgba(0, 0, 0, 0.6), 0 0 20px rgba(229, 169, 60, 0.06);
}

[data-theme="obsidian"] .wordmark-sigil {
  background: #141418;
}

[data-theme="obsidian"] .quote-bezel-core,
[data-theme="obsidian"] .bezel-feature-inner,
[data-theme="obsidian"] .book-jacket-inner,
[data-theme="obsidian"] .colophon-section,
[data-theme="obsidian"] .cards-sampler-section {
  background: #101014;
}

[data-theme="obsidian"] .btn-island-secondary {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.14);
}

[data-theme="obsidian"] .btn-island-secondary:hover {
  background: rgba(255, 255, 255, 0.12);
}

[data-theme="obsidian"] .card-plain-sentence,
[data-theme="obsidian"] .analogy-quote,
[data-theme="obsidian"] .inspector-word-col h3,
[data-theme="obsidian"] .inspector-analogy {
  color: #FFFFFF;
}

[data-theme="obsidian"] .diagram-canvas-enclosure {
  background: #09090C;
}

[data-theme="obsidian"] .sample-word-pill {
  background: #15151B;
  color: #D4D4D8;
  border-color: #272730;
}

[data-theme="obsidian"] .sample-word-pill:hover {
  background: #1E1E26;
  color: #FFF;
}

[data-theme="obsidian"] .sample-word-pill.active {
  background: var(--gold-foil);
  color: #08080A;
  border-color: var(--gold-foil);
  font-weight: 700;
}

[data-theme="obsidian"] .under-card-1 {
  background: #15151B;
}

[data-theme="obsidian"] .under-card-2 {
  background: #0E0E12;
}

/* ==========================================================================
   THEME 3: SWISS ARCHITECTURAL / GALLERY MINIMALIST
   ========================================================================== */
[data-theme="swiss"] {
  --bg-parchment: #F8F9FA;
  --bg-surface: #FFFFFF;
  --bg-subtle: #E9ECEF;
  --bg-card-shell: #E9ECEF;
  --bg-card-core: #FFFFFF;
  
  --ink-primary: #000000;
  --ink-secondary: #2B2D42;
  --ink-tertiary: #6C757D;
  --ink-quaternary: #ADB5BD;
  
  --gold-foil: #D90429; /* Swiss Vermillion Red Accent */
  --gold-light: #EF233C;
  --gold-glow: rgba(217, 4, 41, 0.14);
  --gold-deep: #D90429;
  --gold-border: rgba(217, 4, 41, 0.35);
  
  --serif-title: 'Plus Jakarta Sans', -apple-system, sans-serif;
  --serif-italic: 'Newsreader', Georgia, serif;
  
  --border-hairline: rgba(0, 0, 0, 0.12);
  --border-delicate: #DEE2E6;
  --border-strong: #000000;
  
  --shadow-ambient: 0 20px 50px -15px rgba(0, 0, 0, 0.08);
}

[data-theme="swiss"] .hero-title {
  font-family: var(--sans-ui);
  font-weight: 800;
  letter-spacing: -0.04em;
}

[data-theme="swiss"] .section-h2,
[data-theme="swiss"] .book-main-title {
  font-family: var(--sans-ui);
  font-weight: 750;
  letter-spacing: -0.03em;
}

[data-theme="swiss"] .nav-island {
  border-radius: 6px;
  border: 2px solid #000;
}

[data-theme="swiss"] .card-bezel-outer,
[data-theme="swiss"] .card-bezel-inner,
[data-theme="swiss"] .bezel-feature-card,
[data-theme="swiss"] .bezel-feature-inner,
[data-theme="swiss"] .book-jacket-shell,
[data-theme="swiss"] .book-jacket-inner,
[data-theme="swiss"] .quote-bezel-shell,
[data-theme="swiss"] .quote-bezel-core,
[data-theme="swiss"] .inspector-shell {
  border-radius: 4px;
}

[data-theme="swiss"] .btn-island-primary {
  border-radius: 4px;
  background: #000;
}

[data-theme="swiss"] .btn-island-secondary {
  border-radius: 4px;
  border: 1.5px solid #000;
}

[data-theme="swiss"] .sample-word-pill {
  border-radius: 4px;
  border: 1.5px solid #000;
}

/* ==========================================================================
   Theme Switcher Component in Nav
   ========================================================================== */
.theme-switcher-control {
  display: flex;
  align-items: center;
  gap: 3px;
  background: var(--bg-subtle);
  padding: 3px;
  border-radius: 999px;
  border: 1px solid var(--border-delicate);
}

.theme-pill-btn {
  font-family: var(--mono-code);
  font-size: 0.72rem;
  font-weight: 600;
  padding: 3px 9px;
  border-radius: 999px;
  border: none;
  background: transparent;
  color: var(--ink-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
}

.theme-pill-btn:hover {
  color: var(--ink-primary);
}

.theme-pill-btn.active {
  background: var(--bg-surface);
  color: var(--ink-primary);
  box-shadow: 0 1px 4px rgba(0,0,0,0.08);
}

/* Labor Day Sale Enhancements */
.sale-banner {
  background: #151310;
  color: #FAF7F2;
  padding: 0.65rem 1rem;
  font-family: var(--sans-ui);
  font-size: 0.86rem;
  text-align: center;
  position: relative;
  z-index: 101;
  border-bottom: 1px solid var(--gold-border);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.8rem;
  flex-wrap: wrap;
}

.sale-code-badge {
  background: var(--gold-foil);
  color: #12110F;
  font-family: var(--mono-code);
  font-weight: 700;
  font-size: 0.76rem;
  padding: 0.2rem 0.55rem;
  border-radius: 4px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.price-stack {
  display: flex;
  align-items: baseline;
  gap: 0.45rem;
}

.price-was {
  font-size: 1.05rem;
  color: var(--ink-quaternary);
  text-decoration: line-through;
  font-family: var(--serif-title);
}

.price-now {
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--gold-deep);
  font-family: var(--serif-title);
}

.spine-ai {
  background: linear-gradient(180deg, #6D28D9, #4C1D95);
}

.spine-bundle {
  background: linear-gradient(180deg, #C59B3F, #12110F);
}