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

body {
  background: #f8fafc;
  color: #0f172a;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.5;
}

/* -- Header ---------------------------------------------------------------- */

.site-header {
  align-items: center;
  background: #ffffff;
  border-bottom: 1px solid #e2e8f0;
  display: flex;
  height: 56px;
  justify-content: space-between;
  padding: 0 32px;
}

.wordmark {
  color: #0f172a;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.3px;
  text-decoration: none;
}

.wordmark span {
  color: #4f46e5;
}

.github-link {
  align-items: center;
  color: #64748b;
  display: flex;
  font-size: 13px;
  gap: 6px;
  text-decoration: none;
}

.github-link:hover {
  color: #4f46e5;
}

/* -- Hero ------------------------------------------------------------------ */

.hero {
  background: linear-gradient(135deg, #4338ca 0%, #4f46e5 100%);
  color: #ffffff;
  padding: 80px 32px;
  text-align: center;
}

.hero h1 {
  font-size: 40px;
  font-weight: 800;
  letter-spacing: -0.5px;
  line-height: 1.2;
  margin: 0 auto 16px;
  max-width: 600px;
  text-wrap: balance;
}

.hero p {
  font-size: 18px;
  line-height: 1.6;
  margin: 0 auto 32px;
  max-width: 500px;
  opacity: 0.85;
}

.cta-button {
  background: #ffffff;
  border-radius: 8px;
  color: #4f46e5;
  display: inline-block;
  font-size: 15px;
  font-weight: 600;
  padding: 12px 28px;
  text-decoration: none;
}

.cta-button:hover {
  background: #f1f5f9;
}

/* -- Groups ---------------------------------------------------------------- */

.groups {
  margin: 0 auto;
  max-width: 900px;
  padding: 72px 32px;
}

.groups-label {
  color: #94a3b8;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 1px;
  margin-bottom: 32px;
  text-align: center;
  text-transform: uppercase;
}

.cards-grid {
  display: grid;
  gap: 24px;
  grid-template-columns: 1fr 1fr;
}

.group-card {
  background: #ffffff;
  border-radius: 8px;
  border-top: 3px solid #4f46e5;
  border: 1px solid #e2e8f0;
  padding: 28px;
}

.group-tag {
  color: #4f46e5;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.8px;
  margin-bottom: 4px;
  text-transform: uppercase;
}

.group-card h2 {
  color: #0f172a;
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.3px;
  margin-bottom: 10px;
}

.group-description {
  border-bottom: 1px solid #f1f5f9;
  color: #64748b;
  font-size: 14px;
  line-height: 1.6;
  margin-bottom: 20px;
  padding-bottom: 20px;
}

.group-links {
  display: flex;
  flex-direction: column;
  gap: 10px;
  list-style: none;
}

.group-links a {
  color: #4f46e5;
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
}

.group-links a:hover {
  color: #4338ca;
  text-decoration: underline;
}

/* -- Footer ---------------------------------------------------------------- */

.site-footer {
  background: #ffffff;
  border-top: 1px solid #e2e8f0;
  color: #94a3b8;
  font-size: 13px;
  padding: 28px 32px;
  text-align: center;
}

.site-footer a {
  color: #64748b;
  text-decoration: none;
}

.site-footer a:hover {
  color: #4f46e5;
  text-decoration: underline;
}

.w3c-badge {
  background: #005a9c;
  border-radius: 3px;
  color: #ffffff;
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.3px;
  margin-right: 4px;
  padding: 2px 7px;
}

/* -- Responsive ------------------------------------------------------------ */

@media (max-width: 640px) {
  .site-header {
    padding: 0 16px;
  }

  .hero {
    padding: 56px 16px;
  }

  .hero h1 {
    font-size: 28px;
  }

  .hero p {
    font-size: 16px;
  }

  .groups {
    padding: 48px 16px;
  }

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

  .site-footer {
    padding: 24px 16px;
  }
}