/* Rust Senior Course - Modern Dark Theme */
:root {
  --bg-primary: #0f0f1a;
  --bg-secondary: #1a1a2e;
  --bg-card: #16213e;
  --bg-code: #0d1117;
  --text-primary: #e6e6e6;
  --text-secondary: #a0a0b8;
  --accent: #dea584;
  --accent2: #ce422b;
  --accent3: #69db7c;
  --accent4: #ff6b6b;
  --border: #2a2a4a;
  --gradient-1: linear-gradient(135deg, #ce422b 0%, #dea584 100%);
  --gradient-2: linear-gradient(135deg, #dea584 0%, #69db7c 100%);
  --shadow: 0 4px 20px rgba(0,0,0,0.3);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
}

::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent); }

.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(15, 15, 26, 0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: 0 2rem;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.navbar .logo {
  font-size: 1.4rem;
  font-weight: 800;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  text-decoration: none;
}

.nav-links {
  display: flex;
  gap: 0.3rem;
  align-items: center;
  flex-wrap: wrap;
  justify-content: flex-end;
  max-width: 70%;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.78rem;
  padding: 0.3rem 0.6rem;
  border-radius: 4px;
  transition: all 0.2s;
  white-space: nowrap;
}

.nav-links a:hover, .nav-links a.active {
  color: var(--accent);
  background: rgba(222, 165, 132, 0.1);
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 80px 2rem 2rem;
}

.hero {
  text-align: center;
  padding: 4rem 0 3rem;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 1rem;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 700px;
  margin: 0 auto 2rem;
  line-height: 1.8;
}

.hero .stats {
  display: flex;
  justify-content: center;
  gap: 3rem;
  margin-top: 2rem;
}

.hero .stat-item { text-align: center; }
.hero .stat-number { font-size: 2rem; font-weight: 800; color: var(--accent); display: block; }
.hero .stat-label { font-size: 0.85rem; color: var(--text-secondary); }

.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.2rem;
  margin: 2rem 0;
}

.topic-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  transition: all 0.3s;
  text-decoration: none;
  color: var(--text-primary);
  position: relative;
  overflow: hidden;
}

.topic-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-1);
  opacity: 0;
  transition: opacity 0.3s;
}

.topic-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
  border-color: var(--accent);
}

.topic-card:hover::before { opacity: 1; }

.topic-card .card-number {
  font-size: 2.5rem;
  font-weight: 800;
  opacity: 0.08;
  position: absolute;
  top: 0.3rem;
  right: 0.8rem;
  color: var(--accent);
}

.topic-card h3 { font-size: 1.1rem; margin-bottom: 0.6rem; color: var(--accent); }
.topic-card p { font-size: 0.9rem; color: var(--text-secondary); line-height: 1.6; }

.topic-card .topic-tags {
  display: flex;
  gap: 0.4rem;
  margin-top: 0.8rem;
  flex-wrap: wrap;
}

.topic-card .topic-tags span {
  font-size: 0.7rem;
  padding: 0.15rem 0.5rem;
  border-radius: 10px;
  background: rgba(222, 165, 132, 0.1);
  color: var(--accent2);
  border: 1px solid rgba(222, 165, 132, 0.2);
}

.topic-page { padding: 2rem 0; }

.topic-header {
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
}

.topic-header .back-link {
  color: var(--accent2);
  text-decoration: none;
  font-size: 0.9rem;
  display: inline-block;
  margin-bottom: 1rem;
}

.topic-header .back-link:hover { text-decoration: underline; }
.topic-header h1 { font-size: 2.2rem; font-weight: 800; margin-bottom: 0.5rem; }
.topic-header .topic-meta { color: var(--text-secondary); font-size: 0.9rem; }

.content-section { margin-bottom: 2.5rem; }

.content-section h2 {
  font-size: 1.6rem;
  color: var(--accent);
  margin-bottom: 1rem;
  padding-bottom: 0.3rem;
  border-bottom: 2px solid var(--border);
}

.content-section h3 { font-size: 1.2rem; color: var(--accent2); margin: 1.5rem 0 0.8rem; }
.content-section h4 { font-size: 1.05rem; color: var(--accent3); margin: 1.2rem 0 0.5rem; }
.content-section p { margin-bottom: 1rem; color: var(--text-secondary); line-height: 1.8; }
.content-section ul, .content-section ol { margin: 0.8rem 0 1rem 1.5rem; color: var(--text-secondary); }
.content-section li { margin-bottom: 0.4rem; }
.content-section strong { color: var(--text-primary); }

.content-section blockquote {
  border-left: 4px solid var(--accent);
  padding: 0.8rem 1.2rem;
  margin: 1rem 0;
  background: rgba(222, 165, 132, 0.05);
  border-radius: 0 8px 8px 0;
  color: var(--text-secondary);
}

pre {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.2rem;
  margin: 1rem 0;
  overflow-x: auto;
  font-size: 0.85rem;
  line-height: 1.6;
  font-family: 'Fira Code', 'JetBrains Mono', 'Cascadia Code', monospace;
}

code {
  font-family: 'Fira Code', 'JetBrains Mono', 'Cascadia Code', monospace;
  font-size: 0.85em;
}

p code, li code {
  background: rgba(222, 165, 132, 0.1);
  color: var(--accent);
  padding: 0.1rem 0.4rem;
  border-radius: 4px;
  font-size: 0.8rem;
}

pre code { background: none; padding: 0; color: var(--text-primary); font-size: 0.85rem; }

/* Syntax highlights */
.hl-keyword { color: #ff79c6; }
.hl-builtin { color: #8be9fd; }
.hl-string { color: #f1fa8c; }
.hl-number { color: #bd93f9; }
.hl-comment { color: #6272a4; font-style: italic; }
.hl-function { color: #50fa7b; }
.hl-type { color: #8be9fd; }
.hl-operator { color: #ff79c6; }
.hl-variable { color: #f8f8f2; }
.hl-parameter { color: #ffb86c; }
.hl-self { color: #ff79c6; }
.hl-macro { color: #ffb86c; }
.hl-lifetime { color: #ff5555; }
.hl-attribute { color: #6272a4; }
.hl-trait { color: #8be9fd; }

.info-box {
  background: rgba(222, 165, 132, 0.08);
  border: 1px solid rgba(222, 165, 132, 0.2);
  border-radius: 8px;
  padding: 1rem 1.2rem;
  margin: 1rem 0;
}

.info-box.warning { background: rgba(255, 212, 59, 0.08); border-color: rgba(255, 212, 59, 0.2); }
.info-box.danger { background: rgba(255, 107, 107, 0.08); border-color: rgba(255, 107, 107, 0.2); }
.info-box.success { background: rgba(105, 219, 124, 0.08); border-color: rgba(105, 219, 124, 0.2); }
.info-box strong { display: block; margin-bottom: 0.3rem; }
.info-box code { font-size: 0.8rem; }

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.9rem;
}

.comparison-table th, .comparison-table td {
  padding: 0.7rem 1rem;
  border: 1px solid var(--border);
  text-align: left;
}

.comparison-table th { background: var(--bg-secondary); color: var(--accent); font-weight: 600; }
.comparison-table td { color: var(--text-secondary); }
.comparison-table tr:hover td { background: rgba(222, 165, 132, 0.03); }

.topic-nav {
  display: flex;
  justify-content: space-between;
  padding: 2rem 0;
  margin-top: 2rem;
  border-top: 1px solid var(--border);
}

.topic-nav a {
  color: var(--accent2);
  text-decoration: none;
  font-size: 0.95rem;
  padding: 0.5rem 1rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  transition: all 0.2s;
}

.topic-nav a:hover { background: rgba(222, 165, 132, 0.1); border-color: var(--accent2); }
.topic-nav .nav-disabled { color: var(--border); pointer-events: none; opacity: 0.4; }

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

@media (max-width: 768px) {
  .container { padding: 70px 1rem 1rem; }
  .hero h1 { font-size: 2rem; }
  .hero .stats { flex-direction: column; gap: 1rem; }
  .topic-grid { grid-template-columns: 1fr; }
  .topic-header h1 { font-size: 1.6rem; }
  .nav-links { display: none; }
  .comparison-table { font-size: 0.8rem; }
  .comparison-table th, .comparison-table td { padding: 0.4rem 0.5rem; }
}