:root {
  --bg: #fafbfc;
  --surface: #ffffff;
  --text: #1f2937;
  --text-muted: #6b7280;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --accent: #f59e0b;
  --border: #e5e7eb;
  --code-bg: #111827;
  --radius: 12px;
  --shadow: 0 4px 6px -1px rgba(0,0,0,0.05), 0 2px 4px -1px rgba(0,0,0,0.03);
}

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

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  min-height: 100vh;
}

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

/* Container */
.container { max-width: 1200px; margin: 0 auto; padding: 0 1rem; }

/* Header */
header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow);
}

header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo:hover { text-decoration: none; }

nav { display: flex; gap: 1.5rem; }

nav a {
  color: var(--text-muted);
  font-weight: 500;
  transition: color 0.2s;
}

nav a:hover, nav a.active {
  color: var(--primary);
  text-decoration: none;
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 4rem 1rem 3rem;
  background: linear-gradient(135deg, #eff6ff 0%, #fafbfc 100%);
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 700;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, var(--primary), #7c3aed);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.2rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 2rem;
}

/* Module Grid */
.modules-section {
  padding: 3rem 0;
}

.section-title {
  font-size: 1.8rem;
  font-weight: 600;
  margin-bottom: 2rem;
  text-align: center;
}

.module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.module-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: all 0.3s;
  box-shadow: var(--shadow);
}

.module-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 15px -3px rgba(0,0,0,0.1);
  text-decoration: none;
}

.module-card h3 {
  font-size: 1.2rem;
  margin-bottom: 0.5rem;
  color: var(--text);
}

.module-card p {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 1rem;
}

.module-meta {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.tag {
  background: #dbeafe;
  color: #1e40af;
  font-size: 0.75rem;
  padding: 0.2rem 0.5rem;
  border-radius: 99px;
  font-weight: 600;
}

.tag.green { background: #d1fae5; color: #065f46; }
.tag.purple { background: #ede9fe; color: #5b21b6; }

/* Progress Section */
.progress-section {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 2rem;
  margin-bottom: 3rem;
  border: 1px solid var(--border);
}

.progress-bar {
  background: #e5e7eb;
  height: 8px;
  border-radius: 99px;
  margin: 1rem 0;
  overflow: hidden;
}

.progress-fill {
  background: var(--primary);
  height: 100%;
  border-radius: 99px;
  transition: width 0.5s;
}

/* Footer */
footer {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--text-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
  margin-top: 3rem;
}

/* Breadcrumb */
.breadcrumb {
  padding: 1rem 0;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.breadcrumb a { color: var(--primary); }

/* Responsive */
@media (max-width: 768px) {
  nav { gap: 1rem; font-size: 0.9rem; }
  .hero { padding: 2rem 1rem; }
  .module-grid { grid-template-columns: 1fr; }
}