/* ProgrammingVideoTutorials.com - Modern High-Performance Design System */
:root {
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  
  --bg-primary: #0b0f19;
  --bg-secondary: #111827;
  --bg-tertiary: #1f2937;
  --bg-card: rgba(17, 24, 39, 0.85);
  --bg-card-hover: rgba(31, 41, 55, 0.95);
  
  --text-primary: #f9fafb;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;
  
  --border-color: #374151;
  --border-subtle: #1f2937;
  
  --brand-primary: #3b82f6;
  --brand-hover: #60a5fa;
  --brand-glow: rgba(59, 130, 246, 0.25);
  --brand-gradient: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 50%, #ec4899 100%);
  
  --code-bg: #030712;
  --code-header: #111827;
  --code-text: #e2e8f0;
  
  --ad-bg: rgba(17, 24, 39, 0.5);
  --ad-border: #2d3748;
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-glow: 0 0 25px rgba(59, 130, 246, 0.15);
  
  --container-max: 1200px;
}

[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9;
  --bg-card: #ffffff;
  --bg-card-hover: #f8fafc;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  
  --border-color: #e2e8f0;
  --border-subtle: #f1f5f9;
  
  --brand-primary: #2563eb;
  --brand-hover: #1d4ed8;
  --brand-glow: rgba(37, 99, 235, 0.15);
  
  --code-bg: #0f172a;
  --code-header: #1e293b;
  --code-text: #f8fafc;
  
  --ad-bg: #f1f5f9;
  --ad-border: #cbd5e1;
}

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

html {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--brand-primary);
  text-decoration: none;
  transition: color 0.15s ease;
}

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

img, svg, video {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Layout Container */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Navigation */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(11, 15, 25, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.25rem;
  gap: 1.5rem;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  white-space: nowrap;
}

.brand-logo .logo-icon {
  width: 2.25rem;
  height: 2.25rem;
  background: var(--brand-gradient);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.1rem;
}

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

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-secondary);
  font-weight: 500;
  font-size: 0.95rem;
  padding: 0.4rem 0.6rem;
  border-radius: var(--radius-sm);
  transition: all 0.15s ease;
}

.nav-links a:hover, .nav-links a.active {
  color: var(--text-primary);
  background-color: var(--bg-tertiary);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.theme-toggle-btn {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.5rem;
  border-radius: var(--radius-md);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s ease;
}

.theme-toggle-btn:hover {
  background: var(--border-color);
}

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

/* Hero Section */
.hero {
  padding: 4.5rem 0 3rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.35rem 1rem;
  border-radius: var(--radius-full);
  background: rgba(59, 130, 246, 0.12);
  border: 1px solid rgba(59, 130, 246, 0.3);
  color: var(--brand-hover);
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
}

.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.8rem);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin-bottom: 1.25rem;
}

.hero h1 .gradient-text {
  background: var(--brand-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  max-width: 720px;
  margin: 0 auto 2rem;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 2.5rem;
  margin-top: 2rem;
  flex-wrap: wrap;
}

.stat-item {
  display: flex;
  flex-direction: column;
}

.stat-num {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Search Bar */
.search-container {
  max-width: 600px;
  margin: 0 auto 2rem;
  position: relative;
}

.search-input-wrap {
  display: flex;
  align-items: center;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 0.6rem 1rem;
  box-shadow: var(--shadow-md);
  transition: all 0.2s ease;
}

.search-input-wrap:focus-within {
  border-color: var(--brand-primary);
  box-shadow: var(--shadow-glow);
}

.search-input-wrap input {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text-primary);
  font-size: 1rem;
  outline: none;
  padding-left: 0.75rem;
}

.search-input-wrap input::placeholder {
  color: var(--text-muted);
}

/* Category Grid */
.section-title-wrap {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-bottom: 2rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.section-title {
  font-size: 1.85rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.section-subtitle {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-top: 0.25rem;
}

.category-pills {
  display: flex;
  gap: 0.75rem;
  overflow-x: auto;
  padding-bottom: 0.5rem;
  margin-bottom: 2.5rem;
}

.cat-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius-full);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 600;
  white-space: nowrap;
  transition: all 0.15s ease;
}

.cat-pill:hover, .cat-pill.active {
  background: var(--brand-primary);
  color: white;
  border-color: var(--brand-primary);
}

/* Cards Grid */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.75rem;
  margin-bottom: 3.5rem;
}

.tutorial-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.tutorial-card:hover {
  transform: translateY(-4px);
  border-color: var(--brand-primary);
  box-shadow: var(--shadow-glow);
}

.card-media {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: var(--code-bg);
  overflow: hidden;
}

.card-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.3s ease;
}

.tutorial-card:hover .card-media img {
  transform: scale(1.05);
}

.card-badge {
  position: absolute;
  top: 0.75rem;
  left: 0.75rem;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(4px);
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 600;
  color: white;
  text-transform: uppercase;
}

.video-indicator {
  position: absolute;
  bottom: 0.75rem;
  right: 0.75rem;
  background: rgba(0, 0, 0, 0.8);
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 600;
  color: white;
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.card-body {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  flex: 1;
}

.card-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.card-title {
  font-size: 1.2rem;
  font-weight: 700;
  line-height: 1.35;
  margin-bottom: 0.75rem;
  color: var(--text-primary);
}

.card-excerpt {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin-bottom: 1.25rem;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-footer {
  margin-top: auto;
  padding-top: 1rem;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.85rem;
}

.card-author {
  color: var(--text-secondary);
  font-weight: 500;
}

.read-more-link {
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

/* Ad Spaces (Google AdSense Ready - Zero CLS) */
.ad-slot-wrap {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  margin: 2.5rem 0;
}

.ad-label {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.4rem;
}

.ad-leaderboard {
  min-height: 90px;
  max-width: 728px;
  width: 100%;
  background: var(--ad-bg);
  border: 1px dashed var(--ad-border);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.ad-sidebar {
  min-height: 250px;
  max-width: 300px;
  width: 100%;
  background: var(--ad-bg);
  border: 1px dashed var(--ad-border);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.ad-in-content {
  min-height: 120px;
  width: 100%;
  background: var(--ad-bg);
  border: 1px dashed var(--ad-border);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 2rem 0;
}

.ad-placeholder-text {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-style: italic;
}

/* Tutorial Page Layout */
.tutorial-layout {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 2.5rem;
  padding: 3rem 0;
}

.tutorial-main {
  min-width: 0;
}

.tutorial-header {
  margin-bottom: 2rem;
}

.tutorial-breadcrumbs {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.tutorial-title {
  font-size: clamp(1.8rem, 3.5vw, 2.7rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.tutorial-meta-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.25rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.video-container {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: black;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  margin-bottom: 2.5rem;
}

.video-container iframe {
  width: 100%;
  height: 100%;
  border: none;
}

.objectives-box {
  background: rgba(59, 130, 246, 0.08);
  border-left: 4px solid var(--brand-primary);
  border-radius: var(--radius-sm);
  padding: 1.5rem;
  margin-bottom: 2.5rem;
}

.objectives-box h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.objectives-box ul {
  padding-left: 1.25rem;
}

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

.tutorial-content {
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--text-secondary);
}

.tutorial-content h2 {
  color: var(--text-primary);
  font-size: 1.6rem;
  font-weight: 700;
  margin: 2.5rem 0 1rem;
}

.tutorial-content p {
  margin-bottom: 1.25rem;
}

/* Code Blocks */
.code-block-wrap {
  background: var(--code-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  margin: 1.5rem 0 2rem;
}

.code-header {
  background: var(--code-header);
  padding: 0.5rem 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  border-bottom: 1px solid var(--border-color);
}

.copy-btn {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  padding: 0.25rem 0.6rem;
  font-size: 0.75rem;
  cursor: pointer;
  transition: all 0.15s ease;
}

.copy-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.code-block-wrap pre {
  padding: 1.25rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--code-text);
  line-height: 1.6;
}

.callout-box {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  margin: 1.5rem 0;
  font-size: 0.95rem;
  border-left: 4px solid #f59e0b;
}

/* Interactive Quiz */
.quiz-section {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  margin: 3rem 0;
}

.quiz-section h3 {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
}

.quiz-card {
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  margin-bottom: 1.5rem;
}

.quiz-question {
  font-weight: 600;
  margin-bottom: 1rem;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.quiz-option-btn {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.75rem 1rem;
  text-align: left;
  color: var(--text-primary);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.15s ease;
}

.quiz-option-btn:hover {
  border-color: var(--brand-primary);
  background: var(--bg-card);
}

.quiz-option-btn.correct {
  background: rgba(16, 185, 129, 0.2);
  border-color: #10b981;
  color: #10b981;
}

.quiz-option-btn.wrong {
  background: rgba(239, 68, 68, 0.2);
  border-color: #ef4444;
  color: #ef4444;
}

.quiz-feedback {
  margin-top: 0.75rem;
  font-size: 0.85rem;
  display: none;
}

/* FAQ Accordion */
.faq-section {
  margin: 3rem 0;
}

.faq-item {
  border-bottom: 1px solid var(--border-color);
  padding: 1.25rem 0;
}

.faq-question {
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-answer {
  padding-top: 0.75rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Sidebar Widgets */
.sidebar-sticky {
  position: sticky;
  top: 5.5rem;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.widget-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
}

.widget-title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-subtle);
}

.author-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.author-avatar {
  width: 4rem;
  height: 4rem;
  border-radius: var(--radius-full);
  background: var(--brand-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.author-name {
  font-weight: 700;
  color: var(--text-primary);
}

.author-title {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

/* Footer */
.site-footer {
  margin-top: auto;
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 4rem 0 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: 3rem;
  margin-bottom: 3rem;
}

.footer-brand p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin: 1rem 0;
  max-width: 320px;
}

.footer-col h4 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--text-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.footer-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

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

.footer-bottom {
  padding-top: 2rem;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text-muted);
  font-size: 0.85rem;
  flex-wrap: wrap;
  gap: 1rem;
}

/* Mobile Responsiveness */
@media (max-width: 900px) {
  .tutorial-layout {
    grid-template-columns: 1fr;
  }
  .sidebar-sticky {
    position: static;
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 680px) {
  .nav-links {
    display: none;
  }
  .mobile-menu-btn {
    display: block;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .hero-stats {
    gap: 1.5rem;
  }
}