/* Root Variables */
:root {
  /* C Programming Color Palette */
  --primary-color: #1e3a8a;        /* Deep Blue */
  --secondary-color: #3b82f6;      /* Bright Blue */
  --accent-color: #f97316;         /* Orange */
  --success-color: #10b981;        /* Green */
  --warning-color: #f59e0b;        /* Yellow */
  --error-color: #ef4444;          /* Red */
  
  /* Background Colors */
  --bg-primary: #0f172a;           /* Dark Navy */
  --bg-secondary: #1e293b;         /* Slate Gray */
  --bg-tertiary: #334155;          /* Light Slate */
  
  /* Text Colors */
  --text-primary: #f8fafc;         /* Off White */
  --text-secondary: #cbd5e1;       /* Light Gray */
  --text-muted: #94a3b8;           /* Muted Gray */
  
  /* Glass Effect */
  --glass-bg: rgba(255, 255, 255, 0.1);
  --glass-border: rgba(255, 255, 255, 0.2);
  --glass-shadow: rgba(0, 0, 0, 0.3);
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.2;
  margin-bottom: var(--spacing-md);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

p {
  margin-bottom: var(--spacing-md);
  color: var(--text-secondary);
}

a {
  color: var(--secondary-color);
  text-decoration: none;
  transition: var(--transition-fast);
}

a:hover {
  color: var(--accent-color);
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

/* Navigation */
.navbar {
  position: fixed;
  top: 0;
  width: 100%;
  background: rgba(15, 23, 42, 0.9);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--glass-border);
  z-index: 1000;
  transition: var(--transition-normal);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

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

.nav-icon {
  color: var(--accent-color);
  font-size: 1.75rem;
}

.logo-text {
  color: var(--text-primary);
}

.logo-accent {
  color: var(--accent-color);
}

.nav-menu {
  display: flex;
  gap: var(--spacing-xl);
  list-style: none;
}

.nav-link {
  color: var(--text-secondary);
  font-weight: 500;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-md);
  transition: var(--transition-fast);
  position: relative;
}

.nav-link:hover, .nav-link.active {
  color: var(--text-primary);
  background: var(--glass-bg);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 2px;
  background: var(--accent-color);
  border-radius: 1px;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  cursor: pointer;
  padding: var(--spacing-sm);
}

.bar {
  width: 25px;
  height: 3px;
  background: var(--text-primary);
  margin: 3px 0;
  transition: var(--transition-fast);
  border-radius: 2px;
}

/* Hero Section */
.hero-section {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 70px;
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 50%, var(--bg-primary) 100%);
  position: relative;
  overflow: hidden;
}

.hero-section::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(circle at 20% 50%, rgba(59, 130, 246, 0.1) 0%, transparent 50%),
              radial-gradient(circle at 80% 20%, rgba(249, 115, 22, 0.1) 0%, transparent 50%);
  pointer-events: none;
}

.hero-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-3xl);
  align-items: center;
  position: relative;
  z-index: 1;
}

.hero-content {
  animation: fadeInUp 0.8s ease-out;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  background: var(--glass-bg);
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: 50px;
  border: 1px solid var(--glass-border);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xl);
  backdrop-filter: blur(20px);
}

.hero-badge i {
  color: var(--accent-color);
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: var(--spacing-lg);
  color: var(--text-primary);
}

.text-gradient {
  background: linear-gradient(135deg, var(--secondary-color) 0%, var(--accent-color) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-description {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-2xl);
  max-width: 500px;
}

.hero-buttons {
  display: flex;
  gap: var(--spacing-lg);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-xl);
  border: none;
  border-radius: var(--radius-lg);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-normal);
  text-decoration: none;
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: linear-gradient(135deg, var(--secondary-color) 0%, var(--primary-color) 100%);
  color: white;
  box-shadow: var(--shadow-lg);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-xl);
}

.btn-secondary {
  background: var(--glass-bg);
  color: var(--text-primary);
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(20px);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.15);
  transform: translateY(-2px);
}

/* Hero Visual */
.hero-visual {
  display: flex;
  justify-content: center;
  align-items: center;
  animation: fadeInRight 0.8s ease-out 0.2s both;
}

.code-window {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-xl);
  backdrop-filter: blur(20px);
  box-shadow: var(--shadow-xl);
  overflow: hidden;
  max-width: 500px;
  width: 100%;
}

.code-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md) var(--spacing-lg);
  background: rgba(0, 0, 0, 0.2);
  border-bottom: 1px solid var(--glass-border);
}

.code-buttons {
  display: flex;
  gap: var(--spacing-sm);
}

.code-btn {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.code-btn.red { background: #ff5f57; }
.code-btn.yellow { background: #ffbd2e; }
.code-btn.green { background: #28ca42; }

.code-title {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.code-content {
  padding: var(--spacing-lg);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.875rem;
  line-height: 1.6;
}

.code-content pre {
  margin: 0;
}

.code-include { color: #e879f9; }
.code-keyword { color: #3b82f6; }
.code-function { color: #10b981; }
.code-string { color: #f59e0b; }
.code-number { color: #ef4444; }

/* Topics Section */
.topics-section {
  padding: var(--spacing-3xl) 0;
  background: linear-gradient(180deg, transparent 0%, rgba(30, 58, 138, 0.05) 100%);
}

.section-header {
  text-align: center;
  margin-bottom: var(--spacing-3xl);
}

.section-title {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: var(--spacing-md);
}

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

.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--spacing-xl);
}

.topic-card {
  padding: var(--spacing-xl);
  border-radius: var(--radius-xl);
  cursor: pointer;
  transition: var(--transition-normal);
  border: 1px solid transparent;
}

.topic-card:hover {
  transform: translateY(-8px);
  border-color: var(--glass-border);
  box-shadow: var(--shadow-xl);
}

.topic-icon {
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, var(--secondary-color) 0%, var(--accent-color) 100%);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--spacing-lg);
  font-size: 1.5rem;
  color: white;
}

.topic-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-sm);
}

.topic-description {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-lg);
  line-height: 1.6;
}

.topic-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.topic-lessons {
  color: var(--text-muted);
  font-size: 0.875rem;
}

.topic-difficulty {
  padding: var(--spacing-xs) var(--spacing-md);
  border-radius: 50px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.topic-difficulty.beginner {
  background: rgba(16, 185, 129, 0.2);
  color: var(--success-color);
}

.topic-difficulty.intermediate {
  background: rgba(245, 158, 11, 0.2);
  color: var(--warning-color);
}

.topic-difficulty.advanced {
  background: rgba(239, 68, 68, 0.2);
  color: var(--error-color);
}

/* Features Section */
.features-section {
  padding: var(--spacing-3xl) 0;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-xl);
}

.feature-card {
  text-align: center;
  padding: var(--spacing-2xl);
  border-radius: var(--radius-xl);
  transition: var(--transition-normal);
}

.feature-card:hover {
  transform: translateY(-4px);
}

.feature-icon {
  width: 80px;
  height: 80px;
  background: linear-gradient(135deg, var(--secondary-color) 0%, var(--accent-color) 100%);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--spacing-lg);
  font-size: 2rem;
  color: white;
}

.feature-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-md);
}

.feature-description {
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Resources Section */
.resources-section {
  padding: var(--spacing-3xl) 0;
  background: linear-gradient(180deg, transparent 0%, rgba(30, 58, 138, 0.05) 100%);
}

.resources-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-xl);
}

.resource-card {
  padding: var(--spacing-xl);
  border-radius: var(--radius-xl);
  transition: var(--transition-normal);
}

.resource-card:hover {
  transform: translateY(-4px);
}

.resource-icon {
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, var(--secondary-color) 0%, var(--accent-color) 100%);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--spacing-lg);
  font-size: 1.5rem;
  color: white;
}

.resource-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-sm);
}

.resource-description {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-lg);
  line-height: 1.6;
}

.resource-list {
  list-style: none;
  padding: 0;
}

.resource-list li {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-sm);
  padding-left: var(--spacing-lg);
  position: relative;
}

.resource-list li::before {
  content: '▶';
  position: absolute;
  left: 0;
  color: var(--secondary-color);
  font-size: 0.75rem;
}

/* About Section */
.about-section {
  padding: var(--spacing-3xl) 0;
}

.about-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-3xl);
  align-items: center;
}

.about-description {
  font-size: 1.125rem;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xl);
  line-height: 1.7;
}

.about-stats {
  display: flex;
  gap: var(--spacing-xl);
}

.stat-item {
  text-align: center;
}

.stat-number {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--accent-color);
  margin-bottom: var(--spacing-xs);
}

.stat-label {
  color: var(--text-secondary);
  font-weight: 500;
}

.about-visual {
  display: flex;
  justify-content: center;
}

.about-card {
  padding: var(--spacing-xl);
  border-radius: var(--radius-xl);
  text-align: center;
  max-width: 300px;
}

.about-card h4 {
  color: var(--text-primary);
  margin-bottom: var(--spacing-md);
}

.about-card p {
  color: var(--text-secondary);
  margin-bottom: 0;
}

/* Footer */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--glass-border);
  padding: var(--spacing-3xl) 0 var(--spacing-xl);
  margin-top: var(--spacing-3xl);
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-2xl);
  margin-bottom: var(--spacing-2xl);
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-md);
}

.footer-description {
  color: var(--text-secondary);
  line-height: 1.6;
}

.footer-title {
  color: var(--text-primary);
  font-weight: 600;
  margin-bottom: var(--spacing-lg);
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: var(--spacing-sm);
}

.footer-links a {
  color: var(--text-secondary);
  transition: var(--transition-fast);
}

.footer-links a:hover {
  color: var(--text-primary);
}

.social-links {
  display: flex;
  gap: var(--spacing-md);
}

.social-link {
  width: 40px;
  height: 40px;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.125rem;
  color: var(--text-secondary);
  transition: var(--transition-fast);
}

.social-link:hover {
  background: var(--secondary-color);
  color: white;
  transform: translateY(-2px);
}

.footer-bottom {
  text-align: center;
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--glass-border);
  color: var(--text-muted);
}

/* Animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeInRight {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

/* Responsive Design */
@media (max-width: 768px) {
  /* Navigation */
  .nav-menu {
    position: fixed;
    left: -100%;
    top: 70px;
    flex-direction: column;
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(20px);
    width: 100%;
    text-align: center;
    transition: var(--transition-normal);
    box-shadow: var(--shadow-lg);
    padding: var(--spacing-xl) 0;
    gap: var(--spacing-lg);
  }

  .nav-menu.active {
    left: 0;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-toggle.active .bar:nth-child(2) {
    opacity: 0;
  }

  .nav-toggle.active .bar:nth-child(1) {
    transform: translateY(6px) rotate(45deg);
  }

  .nav-toggle.active .bar:nth-child(3) {
    transform: translateY(-6px) rotate(-45deg);
  }

  /* Hero Section */
  .hero-container {
    grid-template-columns: 1fr;
    text-align: center;
    gap: var(--spacing-2xl);
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    max-width: 300px;
    justify-content: center;
  }

  /* Topics Grid */
  .topics-grid {
    grid-template-columns: 1fr;
  }

  /* Features Grid */
  .features-grid {
    grid-template-columns: 1fr;
  }

  /* Resources Grid */
  .resources-grid {
    grid-template-columns: 1fr;
  }

  /* About Section */
  .about-content {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .about-stats {
    justify-content: center;
  }

  /* Footer */
  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .social-links {
    justify-content: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--spacing-md);
  }

  .nav-container {
    padding: 0 var(--spacing-md);
  }

  .hero-title {
    font-size: 2rem;
  }

  .section-title {
    font-size: 2rem;
  }

  .topic-card,
  .feature-card,
  .resource-card {
    padding: var(--spacing-lg);
  }

  .topics-grid {
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
  }

  .about-stats {
    flex-direction: column;
    gap: var(--spacing-lg);
  }
}

/* Print Styles */
@media print {
  .navbar,
  .hero-visual,
  .footer {
    display: none;
  }

  body {
    background: white;
    color: black;
  }

  .hero-section,
  .topics-section,
  .features-section {
    break-inside: avoid;
  }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
  :root {
    --bg-primary: #000000;
    --bg-secondary: #1a1a1a;
    --text-primary: #ffffff;
    --text-secondary: #e0e0e0;
    --glass-bg: rgba(255, 255, 255, 0.2);
    --glass-border: rgba(255, 255, 255, 0.4);
  }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }
}