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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  color: #1e293b;
  background: #fff;
  -webkit-font-smoothing: antialiased;
}

.nav {
  border-bottom: 1px solid #e2e8f0;
}
.nav-inner {
  max-width: 64rem;
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-left {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  color: #1e293b;
  font-weight: 700;
  font-size: 0.875rem;
}
.nav-icon {
  width: 1.5rem;
  height: 1.5rem;
  border-radius: 0.25rem;
}
.nav-sep { color: #cbd5e1; }
.nav-sub { font-size: 0.875rem; color: #64748b; }
.nav-right { display: flex; gap: 1rem; }
.nav-right a {
  font-size: 0.875rem;
  color: #64748b;
  text-decoration: none;
}
.nav-right a:hover { color: #1e293b; }

.layout {
  max-width: 64rem;
  margin: 0 auto;
  display: flex;
}

.sidebar {
  width: 14rem;
  flex-shrink: 0;
  border-right: 1px solid #f1f5f9;
  padding: 2rem 1.5rem 2rem 1.5rem;
}
.sidebar nav { display: flex; flex-direction: column; gap: 0.25rem; }
.sidebar-link {
  display: block;
  padding: 0.375rem 0.75rem;
  font-size: 0.875rem;
  color: #475569;
  text-decoration: none;
  border-radius: 0.25rem;
}
.sidebar-link:hover { color: #1e293b; background: #f8fafc; }
.sidebar-link.active { color: #1e293b; background: #f1f5f9; font-weight: 500; }

.content {
  flex: 1;
  padding: 2rem 2rem;
  min-width: 0;
  max-width: 48rem;
}

.content h1 {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: #0f172a;
}
.content h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 2rem 0 0.75rem;
  color: #0f172a;
}
.content h3 {
  font-size: 1rem;
  font-weight: 600;
  margin: 1.5rem 0 0.5rem;
  color: #1e293b;
}
.content p {
  font-size: 0.9375rem;
  line-height: 1.7;
  color: #475569;
  margin-bottom: 1rem;
}
.content ul, .content ol {
  margin: 0.5rem 0 1rem 1.25rem;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: #475569;
}
.content li { margin-bottom: 0.375rem; }
.content code {
  font-size: 0.8125rem;
  background: #f1f5f9;
  padding: 0.125rem 0.375rem;
  border-radius: 0.25rem;
  font-family: 'SF Mono', Consolas, monospace;
}
.content strong { color: #1e293b; }

.card-grid {
  display: grid;
  gap: 1rem;
  margin-top: 2rem;
}
.card {
  display: block;
  border: 1px solid #e2e8f0;
  border-radius: 0.5rem;
  padding: 1.25rem;
  text-decoration: none;
  transition: border-color 0.15s;
}
.card:hover { border-color: #93c5fd; }
.card h3 {
  font-size: 0.9375rem;
  font-weight: 600;
  color: #1e293b;
  margin: 0 0 0.25rem;
}
.card p {
  font-size: 0.8125rem;
  color: #64748b;
  margin: 0;
}

.placeholder {
  background: #f8fafc;
  border: 1px solid #e2e8f0;
  border-radius: 0.5rem;
  padding: 2rem;
  text-align: center;
  color: #94a3b8;
  font-size: 0.875rem;
  margin: 2rem 0;
}

@media (max-width: 768px) {
  .sidebar { display: none; }
  .content { padding: 1.5rem; }
}