:root {
  --bg: #ffffff;
  --bg-subtle: #f8f9fb;
  --bg-code: #f4f5f7;
  --surface: #ffffff;
  --border: #e5e7eb;
  --border-light: #f0f1f3;
  --text: #111827;
  --text-secondary: #4b5563;
  --text-tertiary: #9ca3af;
  --accent: #6d28d9;
  --accent-light: #8b5cf6;
  --accent-bg: #f5f3ff;
  --accent-border: #ddd6fe;
  --green: #059669;
  --green-bg: #ecfdf5;
  --blue: #2563eb;
  --orange: #d97706;
  --mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', monospace;
  --sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
}

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

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

/* Top nav bar */
.topnav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
}

.topnav-inner {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
  gap: 24px;
}

.topnav-logo {
  font-weight: 700;
  font-size: 1rem;
  color: var(--text);
  text-decoration: none;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 8px;
}

.topnav-logo-img {
  height: 24px;
  width: auto;
}

.topnav-logo span { color: var(--accent); }

.topnav-links {
  display: flex;
  gap: 24px;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.topnav-links::-webkit-scrollbar { display: none; }

.topnav-links a {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.15s;
  white-space: nowrap;
}

.topnav-links a:hover { color: var(--accent); }
.topnav-links a.active { color: var(--accent); }

/* Hero */
.hero {
  text-align: center;
  padding: 80px 24px 64px;
  background: linear-gradient(180deg, var(--accent-bg) 0%, var(--bg) 100%);
  border-bottom: 1px solid var(--border-light);
}

.hero h1 {
  font-size: 3rem;
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.15;
  margin-bottom: 16px;
}

.hero h1 span { color: var(--accent); }

.hero .subtitle {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 32px;
  line-height: 1.6;
}

.hero-badges {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--accent);
  background: var(--surface);
  border: 1px solid var(--accent-border);
  border-radius: 8px;
  padding: 8px 16px;
  text-decoration: none;
  transition: background 0.15s, border-color 0.15s;
}

.hero-badge:hover {
  background: var(--accent-bg);
  border-color: var(--accent-light);
}

.hero-badge svg {
  width: 16px;
  height: 16px;
}

/* Small hero for sub-pages */
.hero-sm {
  text-align: left;
  padding: 48px 24px 40px;
  background: linear-gradient(180deg, var(--accent-bg) 0%, var(--bg) 100%);
  border-bottom: 1px solid var(--border-light);
}

.hero-sm .hero-inner {
  max-width: 860px;
  margin: 0 auto;
}

.hero-sm h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 8px;
}

.hero-sm h1 span { color: var(--accent); }

.hero-sm .subtitle {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 560px;
  line-height: 1.6;
  margin: 0;
}

.hero-sm .breadcrumb {
  font-size: 0.82rem;
  color: var(--text-tertiary);
  margin-bottom: 12px;
}

.hero-sm .breadcrumb a {
  color: var(--text-tertiary);
  text-decoration: none;
}

.hero-sm .breadcrumb a:hover { color: var(--accent); }

/* Main content */
.container {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 24px;
}

section {
  padding: 64px 0;
}

section + section {
  border-top: 1px solid var(--border-light);
}

h2 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 12px;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 640px;
}

h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 8px;
}

p {
  color: var(--text-secondary);
  margin-bottom: 16px;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Mermaid */
.mermaid-wrapper {
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 32px 16px;
  margin: 32px 0;
  overflow-x: auto;
}

/* Card grid */
.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-top: 28px;
}

@media (max-width: 640px) {
  .card-grid { grid-template-columns: 1fr; }
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.card:hover {
  border-color: var(--accent-border);
  box-shadow: 0 2px 12px rgba(109, 40, 217, 0.06);
}

.card h4 {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 6px;
}

.card p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-bottom: 0;
  line-height: 1.55;
}

/* Guide cards (landing page audience selector) */
.guide-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-top: 20px;
}

@media (max-width: 640px) {
  .guide-grid { grid-template-columns: 1fr; }
}

.guide-card {
  display: block;
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 12px;
  padding: 24px 24px 24px 22px;
  text-decoration: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.guide-card:hover {
  border-color: var(--accent-border);
  border-left-color: var(--accent-light);
  box-shadow: 0 2px 12px rgba(109, 40, 217, 0.08);
  text-decoration: none;
}

.guide-card h4 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 4px;
}

.guide-card p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 0;
  line-height: 1.5;
}

.guide-card .guide-arrow {
  display: inline-block;
  color: var(--accent);
  font-size: 0.82rem;
  font-weight: 500;
  margin-top: 10px;
}

/* Lexicon blocks */
.lexicon-block {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin-bottom: 24px;
  overflow: hidden;
}

.lexicon-header {
  padding: 24px 28px 20px;
  border-bottom: 1px solid var(--border-light);
}

.lexicon-tag {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 600;
  font-family: var(--mono);
  color: var(--accent);
  background: var(--accent-bg);
  border: 1px solid var(--accent-border);
  border-radius: 6px;
  padding: 2px 8px;
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.lexicon-name {
  font-family: var(--mono);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 6px;
  word-break: break-all;
}

.lexicon-desc {
  font-size: 0.92rem;
  color: var(--text-secondary);
  margin-bottom: 0;
  line-height: 1.55;
}

.lexicon-body {
  padding: 0 28px 24px;
}

/* Schema table */
.schema-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  margin: 20px 0 0;
}

.schema-table th {
  text-align: left;
  font-weight: 600;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-tertiary);
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
}

.schema-table td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border-light);
  vertical-align: top;
}

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

.field-name {
  font-family: var(--mono);
  font-weight: 500;
  font-size: 0.84rem;
  color: var(--accent);
  white-space: nowrap;
}

.field-type {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--green);
  white-space: nowrap;
}

.field-type .constraint {
  color: var(--orange);
  font-size: 0.72rem;
  font-weight: 500;
}

.field-desc {
  color: var(--text-secondary);
  font-size: 0.85rem;
}

/* Inline code */
code {
  font-family: var(--mono);
  font-size: 0.85em;
  background: var(--bg-code);
  color: var(--accent);
  padding: 2px 6px;
  border-radius: 4px;
  border: 1px solid var(--border-light);
}

/* Code blocks */
.code-block {
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  margin: 20px 0;
}

.code-label {
  font-size: 0.72rem;
  font-family: var(--mono);
  font-weight: 500;
  color: var(--text-tertiary);
  padding: 10px 16px;
  background: var(--bg-subtle);
  border-bottom: 1px solid var(--border);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

pre {
  padding: 16px;
  font-family: var(--mono);
  font-size: 0.82rem;
  line-height: 1.65;
  overflow-x: auto;
  background: var(--bg-code);
  margin: 0;
}

.hl-key { color: #8b5cf6; }
.hl-str { color: #059669; }
.hl-num { color: #d97706; }
.hl-punc { color: #6b7280; }
.hl-comment { color: #9ca3af; font-style: italic; }

/* Info callout */
.callout {
  background: var(--accent-bg);
  border: 1px solid var(--accent-border);
  border-radius: 10px;
  padding: 20px 24px;
  margin: 24px 0;
}

.callout p { color: var(--text-secondary); margin-bottom: 0; }
.callout strong { color: var(--text); }

/* Steps */
.steps {
  counter-reset: step;
  padding-left: 0;
  list-style: none;
}

.steps li {
  counter-increment: step;
  position: relative;
  padding-left: 40px;
  margin-bottom: 16px;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 1px;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--accent-bg);
  border: 1px solid var(--accent-border);
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
}

/* Trust model list */
.trust-list {
  list-style: none;
  margin-top: 20px;
}

.trust-list li {
  padding: 16px 20px;
  border: 1px solid var(--border);
  border-radius: 10px;
  margin-bottom: 12px;
  background: var(--surface);
}

.trust-list li strong {
  color: var(--text);
  display: block;
  margin-bottom: 2px;
  font-size: 0.92rem;
}

.trust-list li span {
  color: var(--text-secondary);
  font-size: 0.88rem;
}

/* Section sub-heading helper */
.sub-heading { font-size: 0.78rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.06em; color: var(--text-tertiary); margin: 20px 0 4px; }

/* Draft banner */
.draft-banner {
  background: #fef3c7;
  border-bottom: 2px solid #f59e0b;
  padding: 16px 24px;
  text-align: center;
}

.draft-banner p {
  color: #92400e;
  font-size: 0.9rem;
  font-weight: 500;
  margin: 0;
  max-width: 720px;
  margin: 0 auto;
  line-height: 1.5;
}

.draft-banner strong {
  color: #78350f;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 40px 24px;
  text-align: center;
}

footer p {
  font-size: 0.85rem;
  color: var(--text-tertiary);
}

footer a { color: var(--text-tertiary); }
footer a:hover { color: var(--accent); }

/* Responsive */
@media (max-width: 640px) {
  .hero { padding: 48px 24px 40px; }
  .hero h1 { font-size: 2rem; }
  .hero .subtitle { font-size: 1rem; }
  .hero-sm h1 { font-size: 1.5rem; }
  .lexicon-block { overflow: visible; }
  .lexicon-header, .lexicon-body { padding-left: 16px; padding-right: 16px; }
  .lexicon-name { font-size: 0.82rem; overflow-wrap: break-word; word-break: break-word; }
  .topnav-links { gap: 16px; }
  .topnav-links a { font-size: 0.78rem; }
  .card-grid, .guide-grid { grid-template-columns: 1fr; }

  /* Stack schema tables on mobile */
  .schema-table thead { display: none; }
  .schema-table, .schema-table tbody { display: block; }
  .schema-table tr {
    display: block;
    padding: 12px 0;
    border-bottom: 1px solid var(--border-light);
  }
  .schema-table tr:last-child { border-bottom: none; }
  .schema-table td {
    display: block;
    padding: 2px 0;
    border-bottom: none;
  }
  .field-name { font-size: 0.88rem; }
  .field-type { white-space: normal; font-size: 0.76rem; }
  .field-desc { font-size: 0.82rem; margin-top: 4px; }
}