/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   Testing Lattice Model — Design System
   ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */

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

/* ─── Custom Properties (Dark) ────────────── */
:root {
  /* Surfaces */
  --bg-primary: #0B0B0F;
  --bg-secondary: #131318;
  --bg-tertiary: #1A1A22;
  --bg-elevated: #1F1F2A;
  --bg-glass: rgba(25, 25, 38, 0.72);
  --bg-glass-hover: rgba(30, 30, 48, 0.82);

  /* Text */
  --text-primary: #EAEAF0;
  --text-secondary: #9B9BAF;
  --text-tertiary: #6C6C82;
  --text-inverse: #0B0B0F;

  /* Borders */
  --border-primary: rgba(255, 255, 255, 0.08);
  --border-secondary: rgba(255, 255, 255, 0.05);
  --border-accent: rgba(255, 255, 255, 0.12);

  /* Gate Accents */
  --gate-0: #7C6FE0;
  --gate-0-bg: rgba(124, 111, 224, 0.10);
  --gate-0-border: rgba(124, 111, 224, 0.20);
  --gate-1: #34D399;
  --gate-1-bg: rgba(52, 211, 153, 0.10);
  --gate-1-border: rgba(52, 211, 153, 0.20);
  --gate-2: #F59E0B;
  --gate-2-bg: rgba(245, 158, 11, 0.10);
  --gate-2-border: rgba(245, 158, 11, 0.20);
  --gate-3: #FB923C;
  --gate-3-bg: rgba(251, 146, 60, 0.10);
  --gate-3-border: rgba(251, 146, 60, 0.20);
  --gate-4: #F87171;
  --gate-4-bg: rgba(248, 113, 113, 0.10);
  --gate-4-border: rgba(248, 113, 113, 0.20);

  /* Scope Colours */
  --scope-implementation: #7C6FE0;
  --scope-component: #34D399;
  --scope-integration: #F59E0B;
  --scope-system: #FB923C;
  --scope-production: #F87171;

  /* Fault Localisation */
  --fl-high: #34D399;
  --fl-mid: #F59E0B;
  --fl-low: #9B9BAF;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;

  /* Radii */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.5);
  --shadow-glow: 0 0 20px rgba(124, 111, 224, 0.15);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

  /* Layout */
  --max-width: 1200px;
  --nav-height: 60px;

  /* Background Pattern */
  --pattern-line: rgba(124, 111, 224, 0.06);
  --pattern-glow: rgba(124, 111, 224, 0.03);
}

/* ─── Light Theme ─────────────────────────── */
[data-theme="light"] {
  --bg-primary: #F5F5F8;
  --bg-secondary: #FFFFFF;
  --bg-tertiary: #EEEEF2;
  --bg-elevated: #FFFFFF;
  --bg-glass: rgba(255, 255, 255, 0.80);
  --bg-glass-hover: rgba(255, 255, 255, 0.92);

  --text-primary: #1A1A2E;
  --text-secondary: #5C5C72;
  --text-tertiary: #8A8A9E;
  --text-inverse: #EAEAF0;

  --border-primary: rgba(0, 0, 0, 0.08);
  --border-secondary: rgba(0, 0, 0, 0.04);
  --border-accent: rgba(0, 0, 0, 0.12);

  --gate-0: #534AB7;
  --gate-0-bg: rgba(83, 74, 183, 0.08);
  --gate-0-border: rgba(83, 74, 183, 0.16);
  --gate-1: #0F6E56;
  --gate-1-bg: rgba(15, 110, 86, 0.08);
  --gate-1-border: rgba(15, 110, 86, 0.16);
  --gate-2: #BA7517;
  --gate-2-bg: rgba(186, 117, 23, 0.08);
  --gate-2-border: rgba(186, 117, 23, 0.16);
  --gate-3: #D85A30;
  --gate-3-bg: rgba(216, 90, 48, 0.08);
  --gate-3-border: rgba(216, 90, 48, 0.16);
  --gate-4: #A32D2D;
  --gate-4-bg: rgba(163, 45, 45, 0.08);
  --gate-4-border: rgba(163, 45, 45, 0.16);

  --scope-implementation: #534AB7;
  --scope-component: #0F6E56;
  --scope-integration: #BA7517;
  --scope-system: #D85A30;
  --scope-production: #A32D2D;

  --fl-high: #0F6E56;
  --fl-mid: #BA7517;
  --fl-low: #8A8A9E;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.10);
  --shadow-glow: 0 0 20px rgba(83, 74, 183, 0.08);

  --pattern-line: rgba(83, 74, 183, 0.05);
  --pattern-glow: rgba(83, 74, 183, 0.025);
}

/* ─── Base ────────────────────────────────── */
html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  transition: background var(--transition-base), color var(--transition-base);
}

body::after {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    /* Diagonal lattice lines (45°) */
    repeating-linear-gradient(
      45deg,
      var(--pattern-line) 0,
      var(--pattern-line) 1px,
      transparent 1px,
      transparent 40px
    ),
    /* Diagonal lattice lines (−45°) */
    repeating-linear-gradient(
      -45deg,
      var(--pattern-line) 0,
      var(--pattern-line) 1px,
      transparent 1px,
      transparent 40px
    ),
    /* Large ambient glow */
    radial-gradient(
      ellipse at 30% 20%,
      var(--pattern-glow) 0%,
      transparent 50%
    ),
    radial-gradient(
      ellipse at 70% 80%,
      var(--pattern-glow) 0%,
      transparent 50%
    );
  background-size:
    56.57px 56.57px,
    56.57px 56.57px,
    100% 100%,
    100% 100%;
  transition: background-image var(--transition-base);
}

/* Custom scrollbar */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-accent); border-radius: var(--radius-full); }
::-webkit-scrollbar-thumb:hover { background: var(--text-tertiary); }

/* ─── Navigation ─────────────────────────── */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-primary);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-xl);
  transition: background var(--transition-base);
}

.nav-brand {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  letter-spacing: -0.01em;
}

.nav-brand-icon {
  width: 26px;
  height: 26px;
  background: linear-gradient(135deg, var(--gate-0), var(--gate-1));
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  color: #fff;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  list-style: none;
}

.nav-link {
  font-size: 0.8125rem;
  font-weight: 450;
  color: var(--text-secondary);
  text-decoration: none;
  padding: var(--space-xs) var(--space-md);
  border-radius: var(--radius-full);
  transition: color var(--transition-fast), background var(--transition-fast);
  white-space: nowrap;
}

.nav-link:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
}

.nav-link.active {
  color: var(--text-primary);
  background: var(--bg-elevated);
}

.nav-right {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.theme-toggle {
  background: none;
  border: 1px solid var(--border-primary);
  color: var(--text-secondary);
  width: 34px;
  height: 34px;
  border-radius: var(--radius-full);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 15px;
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  color: var(--text-primary);
  border-color: var(--border-accent);
  background: var(--bg-tertiary);
}

/* ─── Main Content ───────────────────────── */
.main {
  padding-top: var(--nav-height);
  min-height: 100vh;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-3xl) var(--space-xl);
}

/* ─── View Transitions ───────────────────── */
.view-enter {
  animation: viewFadeIn 300ms ease forwards;
}

@keyframes viewFadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ─── Hero Section ───────────────────────── */
.hero {
  text-align: center;
  padding: var(--space-4xl) var(--space-xl);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -100px;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(124, 111, 224, 0.06) 0%, transparent 70%);
  pointer-events: none;
}

[data-theme="light"] .hero::before {
  background: radial-gradient(circle, rgba(83, 74, 183, 0.05) 0%, transparent 70%);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-xs) var(--space-md);
  background: var(--gate-0-bg);
  border: 1px solid var(--gate-0-border);
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--gate-0);
  margin-bottom: var(--space-xl);
  letter-spacing: 0.02em;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-lg);
  background: linear-gradient(135deg, var(--text-primary) 40%, var(--gate-0));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto var(--space-2xl);
  line-height: 1.7;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  flex-wrap: wrap;
  margin-bottom: var(--space-2xl);
}

.hero-stat {
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-lg) var(--space-xl);
  min-width: 140px;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.hero-stat:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
}

.hero-stat-number {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.hero-stat-label {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-top: var(--space-xs);
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-xl);
  background: linear-gradient(135deg, var(--gate-0), #5B52C4);
  color: #fff;
  font-size: 0.9375rem;
  font-weight: 500;
  border-radius: var(--radius-full);
  text-decoration: none;
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  box-shadow: 0 2px 12px rgba(124, 111, 224, 0.25);
}

[data-theme="light"] .hero-cta {
  background: linear-gradient(135deg, #534AB7, #3C3489);
  box-shadow: 0 2px 12px rgba(83, 74, 183, 0.20);
}

.hero-cta:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(124, 111, 224, 0.35);
}

.hero-cta-arrow {
  transition: transform var(--transition-fast);
}

.hero-cta:hover .hero-cta-arrow {
  transform: translateX(3px);
}

/* ─── Section Headers ────────────────────── */
.section-header {
  margin-bottom: var(--space-2xl);
}

.section-overline {
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--gate-0);
  margin-bottom: var(--space-sm);
}

.section-title {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-sm);
}

.section-desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  max-width: 600px;
  line-height: 1.7;
}

/* ─── Philosophy Cards ───────────────────── */
.philosophy-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.philosophy-card {
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast);
}

.philosophy-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-accent);
}

.philosophy-card-title {
  font-size: 0.9375rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  letter-spacing: -0.01em;
}

.philosophy-card-body {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ─── Lattice Grid ───────────────────────── */
.lattice-filters {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: var(--space-sm);
  margin-bottom: var(--space-xl);
}

.filter-group {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.filter-label {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-tertiary);
  margin-right: var(--space-xs);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.filter-pill {
  font-size: 0.75rem;
  font-weight: 450;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-primary);
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.filter-pill:hover {
  border-color: var(--border-accent);
  color: var(--text-primary);
}

.filter-pill.active {
  background: var(--bg-elevated);
  border-color: var(--border-accent);
  color: var(--text-primary);
}

.lattice-scroll {
  overflow-x: auto;
  padding-bottom: var(--space-md);
}

.lattice-grid {
  display: grid;
  grid-template-columns: 130px repeat(6, minmax(120px, 1fr));
  gap: 3px;
  min-width: 900px;
}

.lattice-hdr {
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-tertiary);
  padding: var(--space-sm) var(--space-sm);
  text-align: center;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  line-height: 1.3;
}

.lattice-gate {
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: var(--space-md) var(--space-md);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.lattice-gate:hover {
  transform: scale(1.02);
}

.lattice-gate-name {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.lattice-gate-time {
  font-size: 0.6875rem;
  opacity: 0.7;
  margin-top: 2px;
}

.lattice-gate-badge {
  font-size: 0.625rem;
  font-weight: 500;
  margin-top: 6px;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  display: inline-block;
  width: fit-content;
}

.lattice-cell {
  border-radius: var(--radius-md);
  padding: var(--space-sm) var(--space-md);
  cursor: pointer;
  min-height: 76px;
  transition: all var(--transition-fast);
  border: 1px solid transparent;
  display: flex;
  flex-direction: column;
  justify-content: center;
  position: relative;
}

.lattice-cell:hover {
  transform: scale(1.03);
  box-shadow: var(--shadow-md);
  z-index: 2;
}

.lattice-cell.selected {
  border-color: var(--text-primary) !important;
  box-shadow: var(--shadow-lg);
  z-index: 3;
}

.lattice-cell-empty {
  min-height: 76px;
  border-radius: var(--radius-md);
  border: 1px dashed var(--border-primary);
  background: transparent;
  display: flex;
  align-items: center;
  justify-content: center;
}

.lattice-cell-empty-dot {
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--border-primary);
}

.lattice-cell-tool {
  font-size: 0.75rem;
  font-weight: 600;
  line-height: 1.4;
}

.lattice-cell-scope {
  font-size: 0.6875rem;
  opacity: 0.65;
  margin-top: 3px;
  text-transform: capitalize;
}

.lattice-cell-fl {
  position: absolute;
  top: 6px;
  right: 8px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
}

.lattice-cell.dim {
  opacity: 0.15;
  pointer-events: none;
}

/* ─── Detail Panel ───────────────────────── */
.detail-panel {
  margin-top: var(--space-xl);
  background: var(--bg-glass);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-xl) var(--space-2xl);
  animation: panelSlideIn 300ms ease forwards;
}

@keyframes panelSlideIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.detail-panel-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.detail-panel-title {
  font-size: 1.125rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.detail-panel-subtitle {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-top: var(--space-xs);
}

.detail-panel-close {
  background: none;
  border: 1px solid var(--border-primary);
  color: var(--text-secondary);
  width: 30px;
  height: 30px;
  border-radius: var(--radius-full);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  flex-shrink: 0;
  transition: all var(--transition-fast);
}

.detail-panel-close:hover {
  color: var(--text-primary);
  border-color: var(--border-accent);
  background: var(--bg-tertiary);
}

.detail-panel-body {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.75;
  margin-bottom: var(--space-lg);
}

.detail-panel-chips {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.chip {
  font-size: 0.6875rem;
  font-weight: 500;
  padding: 4px 10px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-primary);
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  gap: 5px;
}

.chip-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  flex-shrink: 0;
}

.chip-tool {
  background: var(--bg-elevated);
  border-color: var(--border-accent);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.01em;
}

/* ─── Card Grid (Gates, Attributes) ──────── */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-lg);
}

.card {
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  color: inherit;
  display: block;
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
  border-color: var(--border-accent);
}

.card:hover::before {
  opacity: 1;
}

.card-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  margin-bottom: var(--space-md);
}

.card-title {
  font-size: 1.0625rem;
  font-weight: 600;
  margin-bottom: var(--space-xs);
  letter-spacing: -0.01em;
}

.card-meta {
  font-size: 0.75rem;
  color: var(--text-tertiary);
  margin-bottom: var(--space-md);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.card-body {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.card-footer {
  margin-top: var(--space-lg);
  padding-top: var(--space-md);
  border-top: 1px solid var(--border-secondary);
  font-size: 0.75rem;
  color: var(--text-tertiary);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.card-arrow {
  color: var(--text-tertiary);
  transition: transform var(--transition-fast), color var(--transition-fast);
}

.card:hover .card-arrow {
  transform: translateX(3px);
  color: var(--text-primary);
}

/* ─── Gate Detail Page ───────────────────── */
.gate-detail-header {
  padding: var(--space-2xl) 0;
  border-bottom: 1px solid var(--border-primary);
  margin-bottom: var(--space-2xl);
}

.gate-detail-nav {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-lg);
}

.back-link {
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  transition: color var(--transition-fast);
}

.back-link:hover {
  color: var(--text-primary);
}

.gate-detail-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 500;
  margin-bottom: var(--space-md);
}

.gate-detail-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-sm);
}

.gate-detail-time {
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

.gate-detail-narrative {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.8;
  max-width: 720px;
  margin-top: var(--space-lg);
}

.gate-detail-principle {
  margin-top: var(--space-lg);
  padding: var(--space-md) var(--space-lg);
  border-left: 3px solid;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--bg-tertiary);
  font-size: 0.875rem;
  font-weight: 500;
  letter-spacing: -0.01em;
}

.gate-tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-lg);
}

.gate-tool-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.gate-tool-card:hover {
  border-color: var(--border-accent);
  box-shadow: var(--shadow-sm);
}

.gate-tool-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: var(--space-md);
}

.gate-tool-name {
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.gate-tool-attr {
  font-size: 0.6875rem;
  font-weight: 500;
  padding: 3px 8px;
  border-radius: var(--radius-full);
  background: var(--bg-tertiary);
  color: var(--text-secondary);
}

.gate-tool-body {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-md);
}

.gate-tool-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

/* ─── Tool Catalogue ─────────────────────── */
.tool-search-wrap {
  position: relative;
  margin-bottom: var(--space-xl);
  max-width: 420px;
}

.tool-search {
  width: 100%;
  padding: var(--space-md) var(--space-lg);
  padding-left: 42px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  font-family: var(--font-sans);
  color: var(--text-primary);
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.tool-search::placeholder {
  color: var(--text-tertiary);
}

.tool-search:focus {
  border-color: var(--gate-0);
  box-shadow: 0 0 0 3px var(--gate-0-bg);
}

.tool-search-icon {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-tertiary);
  font-size: 14px;
  pointer-events: none;
}

.tool-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-md);
}

.tool-item {
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  transition: all var(--transition-fast);
  cursor: default;
}

.tool-item:hover {
  border-color: var(--border-accent);
  box-shadow: var(--shadow-sm);
}

.tool-item-name {
  font-size: 0.875rem;
  font-weight: 600;
  font-family: var(--font-mono);
  letter-spacing: -0.01em;
  margin-bottom: var(--space-sm);
}

.tool-item-appearances {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.tool-appearance {
  font-size: 0.75rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.tool-appearance-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  flex-shrink: 0;
}

/* ─── Fault Localisation Page ────────────── */
.fl-diagram {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
  margin: var(--space-2xl) 0;
}

.fl-level-row {
  display: flex;
  align-items: stretch;
  gap: var(--space-lg);
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: border-color var(--transition-fast);
}

.fl-level-row:hover {
  border-color: var(--border-accent);
}

.fl-level-indicator {
  width: 4px;
  border-radius: var(--radius-full);
  flex-shrink: 0;
}

.fl-level-content {
  flex: 1;
}

.fl-level-header {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
}

.fl-level-name {
  font-size: 1.0625rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.fl-level-tag {
  font-size: 0.6875rem;
  font-weight: 500;
  padding: 3px 10px;
  border-radius: var(--radius-full);
}

.fl-level-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-md);
}

.fl-level-gates {
  font-size: 0.75rem;
  color: var(--text-tertiary);
}

/* ─── Comparison Block ───────────────────── */
.comparison-block {
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  margin: var(--space-2xl) 0;
  text-align: center;
}

.comparison-quote {
  font-size: 1.125rem;
  font-weight: 500;
  line-height: 1.7;
  letter-spacing: -0.01em;
  max-width: 640px;
  margin: 0 auto;
}

/* ─── Adoption Section ───────────────────── */
.adoption-block {
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  margin: var(--space-2xl) 0;
}

.adoption-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: var(--space-md);
  letter-spacing: -0.02em;
}

.adoption-body {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.8;
}

/* ─── Gate Timeline (visual) ─────────────── */
.gate-timeline {
  display: flex;
  align-items: center;
  gap: 0;
  margin: var(--space-2xl) 0;
  position: relative;
  overflow-x: auto;
  padding: var(--space-md) 0;
}

.gate-timeline-item {
  flex: 1;
  min-width: 140px;
  text-align: center;
  position: relative;
  padding: 0 var(--space-sm);
}

.gate-timeline-dot {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  margin: 0 auto var(--space-sm);
  position: relative;
  z-index: 2;
  border: 2px solid var(--bg-primary);
  box-shadow: 0 0 0 2px currentColor;
}

.gate-timeline-line {
  position: absolute;
  top: 7px;
  left: 50%;
  right: -50%;
  height: 2px;
  background: var(--border-accent);
  z-index: 1;
}

.gate-timeline-item:last-child .gate-timeline-line {
  display: none;
}

.gate-timeline-name {
  font-size: 0.8125rem;
  font-weight: 600;
  margin-bottom: 2px;
}

.gate-timeline-time {
  font-size: 0.6875rem;
  color: var(--text-tertiary);
}

/* ─── Footer ─────────────────────────────── */
.footer {
  border-top: 1px solid var(--border-primary);
  padding: var(--space-2xl) var(--space-xl);
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-tertiary);
}

/* ─── Stagger Animation ──────────────────── */
.stagger-item {
  opacity: 0;
  animation: staggerFadeIn 400ms ease forwards;
}

@keyframes staggerFadeIn {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ─── Empty State ────────────────────────── */
.empty-state {
  text-align: center;
  padding: var(--space-4xl) var(--space-xl);
  color: var(--text-tertiary);
}

.empty-state-icon {
  font-size: 2rem;
  margin-bottom: var(--space-md);
  opacity: 0.5;
}

.empty-state-text {
  font-size: 0.875rem;
}

/* ─── Responsive ─────────────────────────── */
@media (max-width: 768px) {
  .nav {
    padding: 0 var(--space-md);
  }

  .nav-links {
    display: none;
  }

  .nav-mobile-toggle {
    display: flex;
  }

  .container {
    padding: var(--space-2xl) var(--space-md);
  }

  .hero {
    padding: var(--space-2xl) var(--space-md);
  }

  .hero-stats {
    flex-direction: column;
    align-items: center;
  }

  .hero-stat {
    width: 100%;
    max-width: 280px;
  }

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

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

  .gate-tools-grid {
    grid-template-columns: 1fr;
  }

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

  .fl-level-row {
    flex-direction: column;
  }

  .fl-level-indicator {
    width: 100%;
    height: 4px;
  }

  .detail-panel {
    padding: var(--space-lg);
  }

  .gate-timeline {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-md);
  }

  .gate-timeline-line {
    display: none;
  }

  .lattice-filters {
    flex-direction: column;
    align-items: flex-start;
  }
}

/* ─── Mobile Nav Menu ────────────────────── */
.nav-mobile-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  background: none;
  border: 1px solid var(--border-primary);
  color: var(--text-secondary);
  width: 34px;
  height: 34px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 16px;
  transition: all var(--transition-fast);
}

.nav-mobile-toggle:hover {
  color: var(--text-primary);
  border-color: var(--border-accent);
}

.mobile-menu {
  display: none;
  position: fixed;
  inset: 0;
  top: var(--nav-height);
  background: var(--bg-primary);
  z-index: 99;
  padding: var(--space-xl);
  flex-direction: column;
  gap: var(--space-sm);
}

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

.mobile-menu-link {
  font-size: 1.125rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--border-secondary);
  transition: color var(--transition-fast);
}

.mobile-menu-link:hover,
.mobile-menu-link.active {
  color: var(--text-primary);
}

@media (max-width: 768px) {
  .nav-mobile-toggle {
    display: flex;
  }
}

/* ─── Utilities ──────────────────────────── */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  border: 0;
}

.text-center { text-align: center; }
.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mt-2xl { margin-top: var(--space-2xl); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }