/* Neural Pathways - Portfolio Styles */

:root {
  /* Neural color palette */
  --bg-deep: #0a0a0f;
  --bg-surface: #12121a;
  --bg-elevated: #1a1a25;
  --bg-card: #1e1e2a;
  
  --neural-primary: #6366f1;
  --neural-secondary: #8b5cf6;
  --neural-accent: #a855f7;
  --neural-glow: rgba(139, 92, 246, 0.4);
  
  --synapse-active: #22d3ee;
  --synapse-pulse: #06b6d4;
  
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  
  --success: #10b981;
  --warning: #f59e0b;
  --error: #ef4444;
  
  --border-subtle: rgba(255, 255, 255, 0.06);
  --border-glow: rgba(139, 92, 246, 0.3);
  
  /* Category colors */
  --cat-a: #f472b6; /* Linear Algebra - Pink */
  --cat-b: #fb923c; /* Calculus - Orange */
  --cat-c: #4ade80; /* Neural Ops - Green */
  --cat-d: #60a5fa; /* Optimisation - Blue */
  --cat-e: #c084fc; /* Architecture - Purple */
  --cat-f: #f87171; /* Training - Red */
  --cat-g: #2dd4bf; /* Playgrounds - Teal */
  --cat-h: #fbbf24; /* Advanced - Amber */
  --cat-i: #a78bfa; /* Probability - Violet */
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-deep);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

/* Neural network background animation */
.neural-bg {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  opacity: 0.15;
  pointer-events: none;
}

.neural-bg canvas {
  width: 100%;
  height: 100%;
}

/* Container */
.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* Header */
.header {
  padding: 2rem 0;
  border-bottom: 1px solid var(--border-subtle);
  position: relative;
}

.header::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 50%;
  transform: translateX(-50%);
  width: 200px;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--neural-primary), transparent);
}

.logo {
  display: flex;
  align-items: center;
  gap: 1rem;
  text-decoration: none;
  color: inherit;
}

.logo-icon {
  width: 48px;
  height: 48px;
  position: relative;
}

.logo-icon svg {
  width: 100%;
  height: 100%;
  fill: none;
  stroke: var(--neural-primary);
  stroke-width: 1.5;
}

.logo-text h1 {
  font-size: 1.5rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--neural-primary), var(--neural-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.logo-text span {
  font-size: 0.875rem;
  color: var(--text-muted);
  display: block;
}

/* Hero Section */
.hero {
  padding: 6rem 0 4rem;
  text-align: center;
  position: relative;
}

.hero h1 {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 1.5rem;
}

.hero h1 .gradient-text {
  background: linear-gradient(135deg, var(--neural-primary), var(--synapse-active), var(--neural-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto 2rem;
}

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

.stat {
  text-align: center;
}

.stat-value {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--neural-primary);
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

/* Category Grid */
.categories {
  padding: 4rem 0;
}

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

/* Category Card */
.category-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 16px;
  padding: 1.5rem;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.category-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--category-color);
  opacity: 0.8;
}

.category-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-glow);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3),
              0 0 30px var(--neural-glow);
}

.category-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.category-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: var(--category-color);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  opacity: 0.9;
}

.category-title {
  font-size: 1.125rem;
  font-weight: 600;
}

.category-id {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-left: auto;
  font-family: 'Fira Code', monospace;
}

.category-topics {
  list-style: none;
}

.topic-link {
  display: flex;
  align-items: center;
  padding: 0.75rem;
  margin: 0.25rem 0;
  border-radius: 8px;
  text-decoration: none;
  color: var(--text-secondary);
  transition: all 0.2s ease;
  position: relative;
}

.topic-link:hover {
  background: var(--bg-elevated);
  color: var(--text-primary);
}

.topic-link::before {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--category-color);
  margin-right: 0.75rem;
  opacity: 0.6;
  transition: all 0.2s ease;
}

.topic-link:hover::before {
  opacity: 1;
  box-shadow: 0 0 8px var(--category-color);
}

.topic-id {
  font-family: 'Fira Code', monospace;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-right: 0.5rem;
  min-width: 2rem;
}

.topic-status {
  margin-left: auto;
  font-size: 0.75rem;
}

.status-pending { color: var(--text-muted); }
.status-html { color: var(--warning); }
.status-content { color: var(--synapse-active); }
.status-complete { color: var(--success); }

/* Topic Page Styles */
.topic-page {
  padding: 2rem 0 4rem;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 2rem;
  font-size: 0.875rem;
}

.breadcrumb a {
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.2s ease;
}

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

.breadcrumb span {
  color: var(--text-muted);
}

.topic-header {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border-subtle);
}

.topic-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.topic-badge {
  display: inline-flex;
  align-items: center;
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  font-family: 'Fira Code', monospace;
  background: var(--category-color);
  color: var(--bg-deep);
}

.topic-header h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.topic-description {
  font-size: 1.125rem;
  color: var(--text-secondary);
}

/* Content Layout */
.content-layout {
  display: grid;
  grid-template-columns: 1fr 400px;
  gap: 3rem;
}

@media (max-width: 1024px) {
  .content-layout {
    grid-template-columns: 1fr;
  }
}

/* Visualization Container */
.viz-container {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: 16px;
  aspect-ratio: 16/10;
  display: flex;
  align-items: center;
  justify-content: center;
  position: sticky;
  top: 2rem;
  overflow: hidden;
}

.viz-placeholder {
  text-align: center;
  color: var(--text-muted);
}

.viz-placeholder svg {
  width: 80px;
  height: 80px;
  margin-bottom: 1rem;
  opacity: 0.3;
}

.viz-placeholder p {
  font-size: 0.875rem;
}

/* Full-width Visualization Section */
.viz-fullwidth {
  width: 100%;
  height: 70vh;
  min-height: 500px;
  max-height: 800px;
  margin-bottom: 3rem;
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--border-subtle);
  background: var(--bg-surface);
}

.viz-fullwidth iframe {
  width: 100%;
  height: 100%;
  border: none;
  display: block;
}

/* Single column content layout */
.content-layout--single {
  display: block;
  max-width: 800px;
  margin: 0 auto;
}

/* Educational Content */
.educational-content {
  max-width: 100%;
}

.educational-content h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin: 2rem 0 1rem;
  color: var(--text-primary);
}

.educational-content h2:first-child {
  margin-top: 0;
}

.educational-content h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 1.5rem 0 0.75rem;
  color: var(--text-primary);
}

.educational-content p {
  margin-bottom: 1rem;
  color: var(--text-secondary);
}

.educational-content ul, 
.educational-content ol {
  margin: 1rem 0;
  padding-left: 1.5rem;
}

.educational-content li {
  margin-bottom: 0.5rem;
  color: var(--text-secondary);
}

.educational-content code {
  background: var(--bg-elevated);
  padding: 0.2rem 0.4rem;
  border-radius: 4px;
  font-family: 'Fira Code', monospace;
  font-size: 0.875em;
  color: var(--synapse-active);
}

.educational-content pre {
  background: var(--bg-surface);
  padding: 1rem;
  border-radius: 8px;
  overflow-x: auto;
  margin: 1rem 0;
}

.educational-content pre code {
  background: none;
  padding: 0;
}

.educational-content hr {
  border: none;
  height: 1px;
  background: var(--border-subtle);
  margin: 3rem 0;
}

.educational-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 0.95rem;
}

.educational-content th,
.educational-content td {
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border-subtle);
}

.educational-content th {
  background: var(--bg-elevated);
  color: var(--text-primary);
  font-weight: 600;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.educational-content td {
  color: var(--text-secondary);
}

.educational-content tbody tr:hover {
  background: var(--bg-surface);
}

.educational-content strong {
  color: var(--text-primary);
}

.educational-content em {
  color: var(--text-secondary);
  font-style: italic;
}

/* Navigation between topics */
.topic-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-subtle);
}

.nav-link {
  display: flex;
  flex-direction: column;
  text-decoration: none;
  padding: 1rem;
  border-radius: 12px;
  transition: all 0.2s ease;
  max-width: 45%;
}

.nav-link:hover {
  background: var(--bg-card);
}

.nav-link.prev {
  align-items: flex-start;
}

.nav-link.next {
  align-items: flex-end;
  text-align: right;
}

.nav-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 0.25rem;
}

.nav-title {
  color: var(--text-primary);
  font-weight: 600;
}

/* Back to top / Home button */
.back-home {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--neural-primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  box-shadow: 0 4px 20px var(--neural-glow);
  transition: all 0.2s ease;
}

.back-home:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px var(--neural-glow);
}

/* Footer */
.footer {
  padding: 3rem 0;
  border-top: 1px solid var(--border-subtle);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.875rem;
}

/* Utility classes */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

/* Glow effects */
@keyframes pulse-glow {
  0%, 100% { opacity: 0.4; }
  50% { opacity: 0.8; }
}

.glow {
  animation: pulse-glow 3s ease-in-out infinite;
}

/* Responsive */
@media (max-width: 768px) {
  .container {
    padding: 0 1rem;
  }
  
  .hero {
    padding: 4rem 0 2rem;
  }
  
  .hero-stats {
    gap: 1.5rem;
  }
  
  .stat-value {
    font-size: 1.75rem;
  }
  
  .categories-grid {
    grid-template-columns: 1fr;
  }
  
  .topic-header h1 {
    font-size: 1.75rem;
  }
}