:root {
  --primary: #3b82f6;
  --primary-dark: #2563eb;
  --primary-light: #60a5fa;
  --primary-50: #eff6ff;
  --primary-100: #dbeafe;
  --secondary: #8b5cf6;
  --accent: #10b981;
  --accent-600: #059669;
  --danger: #ef4444;
  --warning: #f59e0b;
  --light: #f8fafc;
  --dark: #1e293b;
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --border: #e2e8f0;
  --shadow: rgba(0,0,0,0.1);
  --card-bg: #ffffff;
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --space-xs: clamp(0.25rem, 0.5vw, 0.5rem);
  --space-sm: clamp(0.5rem, 1vw, 0.75rem);
  --space-md: clamp(0.75rem, 2vw, 1rem);
  --space-lg: clamp(1rem, 3vw, 1.5rem);
  --space-xl: clamp(1.5rem, 4vw, 2rem);
  --gradient-primary: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
}

[data-theme="dark"] {
  --primary: #60a5fa;
  --light: #0f172a;
  --dark: #f1f5f9;
  --border: #334155;
  --shadow: rgba(0,0,0,0.3);
  --card-bg: #1e293b;
  --gray-50: #1e293b;
  --gray-100: #334155;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  color: var(--dark);
  background: var(--light);
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.3s, color 0.3s;
}
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--primary);
  color: #fff;
  padding: 8px 16px;
  z-index: 10000;
  text-decoration: none;
  border-radius: 0 0 4px 0;
}
.skip-link:focus { top: 0; }
.ad-container {
  min-height: 90px;
  display: block;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--card-bg);
  overflow: hidden;
  margin: 1rem 0;
}
.ad-container:empty::before {
  content: 'Advertisement';
  display: flex;
  align-items: center;
  justify-content: center;
  height: 90px;
  color: var(--gray-400);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}
.ad-container.loaded { border-color: transparent; }