/* CSS Reset and Variables */
:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --text-primary: #e6edf3;
  --text-secondary: #7d8590;
  --accent-primary: #58a6ff;
  --accent-secondary: #1f6feb;
  --accent-success: #3fb950;
  --accent-warning: #d29922;
  --accent-error: #f85149;
  --code-bg: #0d1117;
  --border: #30363d;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
  --max-width: 1200px;
  --transition: all 0.2s ease;
}

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

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--accent-primary);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--accent-secondary);
  text-decoration: underline;
}

img {
  max-width: 100%;
  height: auto;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 1rem;
}

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

p {
  margin-bottom: 1rem;
}

/* Container */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header */
.header {
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

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

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

.logo:hover {
  color: var(--text-primary);
  text-decoration: none;
}

.logo svg {
  width: 40px;
  height: 40px;
}

.nav {
  display: flex;
  gap: 2rem;
}

.nav a {
  color: var(--text-secondary);
  font-weight: 500;
}

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

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 1.5rem;
  cursor: pointer;
}

/* Hero Section */
.hero {
  padding: 6rem 0;
  text-align: center;
  background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.hero h1 {
  font-size: 3.5rem;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent-primary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero .tagline {
  font-size: 1.5rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto 2rem;
}

.hero .cta-buttons {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: 6px;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

.btn-primary {
  background-color: var(--accent-secondary);
  color: white;
}

.btn-primary:hover {
  background-color: var(--accent-primary);
  text-decoration: none;
  color: white;
}

.btn-secondary {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background-color: var(--border);
  text-decoration: none;
}

/* Cards */
.card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.5rem;
  transition: var(--transition);
}

.card:hover {
  border-color: var(--accent-primary);
  transform: translateY(-2px);
}

.card h3 {
  margin-bottom: 0.75rem;
}

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

/* Grid Layouts */
.grid {
  display: grid;
  gap: 1.5rem;
}

.grid-2 {
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

/* Sections */
.section {
  padding: 4rem 0;
}

.section-header {
  text-align: center;
  margin-bottom: 3rem;
}

.section-header h2 {
  margin-bottom: 0.5rem;
}

.section-header p {
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* Featured Series */
.featured-series {
  background-color: var(--bg-secondary);
  border-radius: 12px;
  padding: 3rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.featured-series-content h2 {
  font-size: 2rem;
}

.featured-series-content .badge {
  display: inline-block;
  background-color: var(--accent-warning);
  color: var(--bg-primary);
  padding: 0.25rem 0.75rem;
  border-radius: 4px;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 1rem;
}

.featured-series-topics {
  list-style: none;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
}

.featured-series-topics li {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-secondary);
}

.featured-series-topics li::before {
  content: '';
  width: 6px;
  height: 6px;
  background-color: var(--accent-primary);
  border-radius: 50%;
}

/* Blog Cards */
.blog-card {
  display: flex;
  flex-direction: column;
}

.blog-card .meta {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

/* Quiz Card */
.quiz-card {
  text-align: center;
}

.quiz-card .question-count {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--accent-primary);
}

/* Resource Categories */
.resource-category {
  margin-bottom: 3rem;
}

.resource-category h3 {
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--accent-primary);
}

.resource-list {
  display: grid;
  gap: 1rem;
}

.resource-item {
  display: flex;
  gap: 1rem;
  padding: 1rem;
  background-color: var(--bg-secondary);
  border-radius: 6px;
  border: 1px solid var(--border);
}

.resource-item:hover {
  border-color: var(--accent-primary);
}

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

.footer-content {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 3rem;
}

.footer-brand p {
  color: var(--text-secondary);
  margin-top: 1rem;
}

.footer-links h4 {
  color: var(--text-primary);
  margin-bottom: 1rem;
  font-size: 1rem;
}

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

.footer-links li {
  margin-bottom: 0.5rem;
}

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

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

.footer-bottom {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--text-secondary);
}

.social-links {
  display: flex;
  gap: 1rem;
  margin-top: 1rem;
}

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background-color: var(--bg-tertiary);
  border-radius: 8px;
  color: var(--text-secondary);
  transition: var(--transition);
}

.social-links a:hover {
  background-color: var(--accent-secondary);
  color: white;
}

/* Code Blocks */
pre {
  background-color: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  overflow-x: auto;
  margin-bottom: 1rem;
}

code {
  font-family: var(--font-mono);
  font-size: 0.9rem;
}

:not(pre) > code {
  background-color: var(--bg-tertiary);
  padding: 0.2rem 0.4rem;
  border-radius: 4px;
}

/* Quiz Styles */
.quiz-container {
  max-width: 900px;
  margin: 0 auto;
}

.quiz-header h2 {
  font-size: 2.5rem;
  margin-bottom: 0.75rem;
}

.quiz-header p {
  font-size: 1.25rem;
  color: var(--text-secondary);
}

.quiz-question {
  background-color: rgba(88, 166, 255, 0.08);
  border: 2px solid rgba(88, 166, 255, 0.3);
  border-radius: 12px;
  padding: 2.5rem;
  margin-bottom: 1.5rem;
}

.quiz-question h3 {
  font-size: 1.75rem;
  margin-bottom: 2rem;
  line-height: 1.4;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.quiz-option {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  padding: 1.25rem 1.5rem;
  background-color: rgba(88, 166, 255, 0.12);
  border: 2px solid rgba(88, 166, 255, 0.25);
  border-radius: 10px;
  cursor: pointer;
  transition: var(--transition);
  font-size: 1.2rem;
  color: var(--text-primary);
  text-align: left;
}

.quiz-option:hover {
  border-color: var(--accent-primary);
  background-color: rgba(88, 166, 255, 0.2);
}

.quiz-option.selected {
  border-color: var(--accent-primary);
  background-color: rgba(88, 166, 255, 0.2);
}

.quiz-option.correct {
  border-color: var(--accent-success);
  background-color: rgba(63, 185, 80, 0.25);
}

.quiz-option.incorrect {
  border-color: var(--accent-error);
  background-color: rgba(248, 81, 73, 0.25);
}

.quiz-explanation {
  margin-top: 1.5rem;
  padding: 1.5rem;
  background-color: var(--bg-tertiary);
  border-radius: 8px;
  border-left: 4px solid var(--accent-primary);
  font-size: 1.15rem;
  line-height: 1.6;
}

.quiz-results {
  text-align: center;
  padding: 3rem;
  background-color: var(--bg-secondary);
  border-radius: 12px;
}

.quiz-score {
  font-size: 5rem;
  font-weight: 700;
  color: var(--accent-primary);
}

/* Coming Soon Badge */
.coming-soon {
  background: linear-gradient(135deg, var(--accent-warning) 0%, var(--accent-error) 100%);
  color: var(--bg-primary);
  padding: 0.25rem 0.75rem;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* Page Header */
.page-header {
  padding: 4rem 0 2rem;
  text-align: center;
  background-color: var(--bg-secondary);
  margin-bottom: 3rem;
}

.page-header h1 {
  margin-bottom: 0.5rem;
}

.page-header p {
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* Blog Post */
.blog-content {
  max-width: 800px;
  margin: 0 auto;
}

.blog-content h2,
.blog-content h3 {
  margin-top: 2rem;
}

.blog-content ul,
.blog-content ol {
  margin-left: 1.5rem;
  margin-bottom: 1rem;
}

.blog-content li {
  margin-bottom: 0.5rem;
}

/* Series Episode List */
.episode-list {
  list-style: none;
}

.episode-item {
  display: flex;
  gap: 1rem;
  padding: 1rem;
  border-bottom: 1px solid var(--border);
}

.episode-item:last-child {
  border-bottom: none;
}

.episode-number {
  font-weight: 700;
  color: var(--accent-primary);
  font-size: 1.25rem;
  min-width: 2rem;
}

/* Responsive */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2.5rem;
  }

  .hero .tagline {
    font-size: 1.25rem;
  }

  .nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--bg-secondary);
    padding: 1rem;
    flex-direction: column;
    gap: 1rem;
    border-bottom: 1px solid var(--border);
  }

  .nav.active {
    display: flex;
  }

  .mobile-menu-btn {
    display: block;
  }

  .featured-series {
    grid-template-columns: 1fr;
    padding: 2rem;
  }

  .featured-series-topics {
    grid-template-columns: 1fr;
  }

  .footer-content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 2rem;
  }

  .section {
    padding: 2rem 0;
  }

  .card {
    padding: 1rem;
  }
}