:root {
  --bg: #ffffff;
  --bg-alt: #f9fafb;
  --card: #ffffff;
  --text: #111827;
  --text-secondary: #6b7280;
  --border: #e5e7eb;
  --accent: #111827;
  --accent-hover: #374151;
  --tag-bg: #f3f4f6;
  --tag-text: #4b5563;
}

body.dark {
  --bg: #0a0a0a;
  --bg-alt: #111111;
  --card: #171717;
  --text: #fafafa;
  --text-secondary: #a1a1aa;
  --border: #27272a;
  --accent: #fafafa;
  --accent-hover: #d4d4d8;
  --tag-bg: #27272a;
  --tag-text: #a1a1aa;
}

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

body {
  font-family: "Inter", -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  max-width: 100%;
  display: block;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.6);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

body.dark .site-header {
  background: rgba(10, 10, 10, 0.6);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
}

.nav {
  max-width: 1200px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.logo {
  display: flex;
  align-items: center;
}

.logo img {
  height: 28px;
  width: auto;
}

.nav-links {
  display: flex;
  gap: 32px;
  font-size: 0.9375rem;
  font-weight: 500;
}

.nav-links a {
  color: var(--text-secondary);
  transition: color 0.15s;
}

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

body[data-page="datasets"] .nav-links a[data-page="datasets"],
body[data-page="about"] .nav-links a[data-page="about"] {
  color: var(--text);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.github-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  transition: all 0.15s;
}

.github-btn:hover {
  color: var(--text);
  background: var(--bg-alt);
}

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 1rem;
  transition: all 0.15s;
}

.theme-toggle:hover {
  color: var(--text);
  background: var(--bg-alt);
}

/* Main */
main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Hero - Homepage */
.hero-modern {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
  padding: 80px 0 60px;
  min-height: 70vh;
}

.hero-text h1 {
  font-size: clamp(2.5rem, 5vw, 3.5rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin-bottom: 24px;
}

.hero-description {
  font-size: 1.125rem;
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 480px;
}

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

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  background: var(--text);
  color: var(--bg);
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.9375rem;
  transition: all 0.15s;
}

.btn-primary:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.9375rem;
  transition: all 0.15s;
}

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

.hero-image {
  display: flex;
  justify-content: center;
}

.hero-image img {
  max-width: 100%;
}

body.dark .hero-image img {
  /* no shadow, flat display */
}

/* Stats Bar */
.stats-bar {
  display: flex;
  justify-content: center;
  gap: 64px;
  padding: 40px 0;
  border-top: 1px solid var(--border);
  margin-bottom: 40px;
}

.stat {
  text-align: center;
}

.stat-number {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

/* Page Header */
.page-header {
  padding: 60px 0 40px;
}

.page-header-content h1 {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 12px;
}

.page-subtitle {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 600px;
}

/* Search Section */
.search-section {
  padding-bottom: 32px;
}

.search-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin-bottom: 20px;
}

.search-icon {
  color: var(--text-secondary);
  flex-shrink: 0;
}

.search-bar input {
  flex: 1;
  border: none;
  background: transparent;
  font-size: 1rem;
  color: var(--text);
  outline: none;
}

.search-bar input::placeholder {
  color: var(--text-secondary);
}

.clear-btn {
  padding: 6px 12px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 0.875rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s;
}

.clear-btn:hover {
  background: var(--card);
  color: var(--text);
}

.filter-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.filter-chip {
  padding: 6px 14px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: transparent;
  cursor: pointer;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: all 0.15s;
}

.filter-chip:hover {
  background: var(--bg-alt);
  color: var(--text);
}

.filter-chip.active {
  background: var(--text);
  color: var(--bg);
  border-color: transparent;
}

/* Datasets Section */
.datasets-section {
  padding-bottom: 80px;
}

.results-count {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.dataset-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 16px;
}

.dataset-card {
  background: var(--card);
  padding: 20px;
  border-radius: 12px;
  border: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: all 0.15s;
}

.dataset-card:hover {
  border-color: var(--text-secondary);
}

.dataset-card h3 {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.4;
}

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

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  padding: 3px 8px;
  border-radius: 4px;
  background: var(--tag-bg);
  color: var(--tag-text);
  font-size: 0.75rem;
  font-weight: 500;
}

.dataset-links {
  margin-top: auto;
  display: flex;
  gap: 16px;
}

.dataset-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text);
  transition: opacity 0.15s;
}

.dataset-link:hover {
  opacity: 0.7;
}

.dataset-link svg {
  transition: transform 0.15s;
}

.dataset-link:hover svg {
  transform: translateX(2px);
}

/* About Page */
.about-content {
  padding-bottom: 80px;
  max-width: 800px;
}

.about-section {
  margin-bottom: 48px;
}

.about-section h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 16px;
  letter-spacing: -0.01em;
}

.about-section p {
  color: var(--text-secondary);
  line-height: 1.7;
}

.category-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
  margin-top: 16px;
}

.category-item {
  padding: 16px;
  background: var(--bg-alt);
  border-radius: 8px;
  border: 1px solid var(--border);
}

.category-item h3 {
  font-size: 0.9375rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.category-item p {
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

.label-tags {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: 12px;
}

.label-group {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.label-group strong {
  color: var(--text);
}

.resource-links {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 8px;
  margin-top: 16px;
}

.resource-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 12px 16px;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text);
  transition: all 0.15s;
}

.resource-link:hover {
  background: var(--card);
  border-color: var(--text-secondary);
}

.resource-link svg {
  transition: transform 0.15s;
}

.resource-link:hover svg {
  transform: translateX(2px);
}

.contact-section {
  padding: 32px;
  background: var(--bg-alt);
  border-radius: 12px;
  border: 1px solid var(--border);
}

.contact-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: 16px;
  padding: 12px 24px;
  background: var(--text);
  color: var(--bg);
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.9375rem;
  transition: all 0.15s;
}

.contact-btn:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

/* Footer */
.footer {
  border-top: 1px solid var(--border);
  background: var(--bg);
  padding: 32px 24px;
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 24px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 8px;
}

.footer-brand strong {
  font-weight: 600;
}

.footer-tagline {
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.footer-links {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.footer-links a {
  font-size: 0.875rem;
  color: var(--text-secondary);
  transition: color 0.15s;
}

.footer-links a:hover {
  color: var(--text);
}

.footer-copyright {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

/* Responsive */
@media (max-width: 900px) {
  .hero-modern {
    grid-template-columns: 1fr;
    gap: 40px;
    padding: 40px 0;
    min-height: auto;
  }

  .hero-image {
    order: -1;
  }

  .stats-bar {
    gap: 32px;
  }
}

@media (max-width: 600px) {
  .nav {
    flex-wrap: wrap;
  }

  .nav-links {
    gap: 20px;
    order: 3;
    width: 100%;
    margin-top: 12px;
  }

  .page-header-content h1 {
    font-size: 2rem;
  }

  .hero-text h1 {
    font-size: 2rem;
  }

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

  .footer-content {
    flex-direction: column;
    text-align: center;
  }
}