/* AI Learning App - Mobile First CSS */

/* CSS Variables */
:root {
  /* Colors - Light Mode */
  --bg-primary: #f8fafc;
  --bg-secondary: #e2e8f0;
  --bg-card: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --accent-light: #e0e7ff;
  --success: #22c55e;
  --border: #e2e8f0;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;

  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SF Mono', Monaco, 'Cascadia Code', monospace;

  /* Sizes */
  --header-height: 60px;
  --max-width: 800px;
  --border-radius: 12px;
  --border-radius-sm: 8px;

  /* Transitions */
  --transition: 0.2s ease;
}

/* Dark Mode */
[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-card: #1e293b;
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent: #818cf8;
  --accent-hover: #a5b4fc;
  --accent-light: #312e81;
  --border: #334155;
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  min-height: 100dvh;
  transition: background var(--transition), color var(--transition);
}

/* Typography */
h1, h2, h3, h4 {
  line-height: 1.3;
  font-weight: 700;
}

h1 { font-size: 1.75rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.1rem; }

p { margin-bottom: var(--space-md); }

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

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

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

/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  display: flex;
  align-items: center;
  transition: background var(--transition), border var(--transition);
}

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

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.logo-icon {
  width: 28px;
  height: 28px;
}

/* Theme Toggle */
.theme-toggle {
  width: 44px;
  height: 44px;
  border: none;
  background: transparent;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--border-radius-sm);
  transition: background var(--transition);
}

.theme-toggle:hover {
  background: var(--bg-secondary);
}

.theme-toggle svg {
  width: 24px;
  height: 24px;
  fill: var(--text-primary);
}

/* Main Content */
main {
  padding-top: calc(var(--header-height) + var(--space-lg));
  padding-bottom: var(--space-2xl);
  min-height: 100vh;
}

/* Progress Bar */
.progress-bar {
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  height: 4px;
  background: var(--bg-secondary);
  z-index: 99;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #22d3ee);
  transition: width 0.3s ease;
  border-radius: 0 2px 2px 0;
}

/* Step Overview Cards */
.step-grid {
  display: grid;
  gap: var(--space-md);
  margin-top: var(--space-lg);
}

.step-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
  display: flex;
  gap: var(--space-md);
  align-items: flex-start;
  transition: all var(--transition);
  text-decoration: none;
  color: inherit;
}

.step-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.15);
}

.step-card.completed {
  border-left: 4px solid var(--success);
}

.step-number {
  width: 40px;
  height: 40px;
  min-width: 40px;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
}

.step-card.completed .step-number {
  background: var(--success);
  color: white;
}

.step-content h3 {
  margin-bottom: var(--space-xs);
}

.step-content p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin: 0;
}

/* Step Page */
.step-header {
  margin-bottom: var(--space-xl);
}

.step-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  background: var(--accent-light);
  color: var(--accent);
  padding: var(--space-xs) var(--space-md);
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
}

/* Content Sections */
.content-section {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.content-section h2 {
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--accent-light);
}

/* Info Box */
.info-box {
  background: var(--accent-light);
  border-left: 4px solid var(--accent);
  padding: var(--space-md);
  border-radius: 0 var(--border-radius-sm) var(--border-radius-sm) 0;
  margin: var(--space-md) 0;
}

.info-box p {
  margin: 0;
  color: var(--text-primary);
}

/* Service Cards */
.service-grid {
  display: grid;
  gap: var(--space-md);
}

.service-card {
  background: var(--bg-secondary);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.service-card h4 {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.service-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin: 0;
  flex-grow: 1;
}

.service-card .tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-top: var(--space-sm);
}

.tag {
  background: var(--bg-primary);
  color: var(--text-muted);
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
}

/* Tech Stack Details (expandable) */
.tech-stack-details {
  margin-top: var(--space-sm);
  border-top: 1px solid var(--border);
  padding-top: var(--space-sm);
}

.tech-stack-details summary {
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 0.85rem;
  font-weight: 500;
  list-style: none;
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.tech-stack-details summary::-webkit-details-marker {
  display: none;
}

.tech-stack-details summary::before {
  content: '▶';
  font-size: 0.7rem;
  transition: transform var(--transition);
}

.tech-stack-details[open] summary::before {
  transform: rotate(90deg);
}

.tech-stack-details ul {
  margin-top: var(--space-sm);
  padding-left: var(--space-md);
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.tech-stack-details li {
  margin-bottom: var(--space-xs);
}

.tech-stack-details li strong {
  color: var(--text-primary);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--border-radius-sm);
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: all var(--transition);
  border: none;
  text-decoration: none;
  min-height: 44px;
}

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

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

.btn-secondary {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.btn-secondary:hover {
  background: var(--border);
}

.btn-demo {
  background: linear-gradient(135deg, var(--accent), #22d3ee);
  color: white;
  width: 100%;
  margin-top: var(--space-sm);
}

.btn-demo:hover {
  opacity: 0.9;
  color: white;
}

/* Navigation */
.step-nav {
  display: flex;
  justify-content: space-between;
  gap: var(--space-md);
  margin-top: var(--space-xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--border);
}

.step-nav .btn {
  flex: 1;
  max-width: 180px;
}

.step-nav .btn:only-child {
  margin-left: auto;
}

/* Lists */
.feature-list {
  list-style: none;
  padding: 0;
}

.feature-list li {
  padding: var(--space-sm) 0;
  padding-left: var(--space-lg);
  position: relative;
}

.feature-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 8px;
  height: 8px;
  background: var(--accent);
  border-radius: 50%;
}

/* Comparison Table */
.comparison-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  margin: var(--space-md) 0;
}

.comparison-table th,
.comparison-table td {
  padding: var(--space-sm) var(--space-md);
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.comparison-table th {
  background: var(--bg-secondary);
  font-weight: 600;
}

.comparison-table tr:hover td {
  background: var(--bg-secondary);
}

/* Hero Section */
.hero {
  text-align: center;
  padding: var(--space-xl) 0;
}

.hero h1 {
  font-size: 2rem;
  margin-bottom: var(--space-md);
}

.hero p {
  color: var(--text-secondary);
  font-size: 1.1rem;
  max-width: 500px;
  margin: 0 auto var(--space-lg);
}

/* Quiz */
.quiz-card {
  background: var(--bg-card);
  border: 2px solid var(--border);
  border-radius: var(--border-radius);
  padding: var(--space-lg);
  margin: var(--space-lg) 0;
}

.quiz-card h4 {
  margin-bottom: var(--space-md);
  color: var(--accent);
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.quiz-option {
  padding: var(--space-md);
  background: var(--bg-secondary);
  border: 2px solid transparent;
  border-radius: var(--border-radius-sm);
  cursor: pointer;
  transition: all var(--transition);
}

.quiz-option:hover {
  border-color: var(--accent);
}

.quiz-option.correct {
  border-color: var(--success);
  background: rgba(34, 197, 94, 0.1);
}

.quiz-option.incorrect {
  border-color: #ef4444;
  background: rgba(239, 68, 68, 0.1);
}

/* Footer */
.footer {
  background: var(--bg-card);
  border-top: 1px solid var(--border);
  padding: var(--space-lg) 0;
  margin-top: auto;
}

.footer-content {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  text-align: center;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  flex-wrap: wrap;
}

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

.footer-credit {
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* Tablet */
@media (min-width: 768px) {
  h1 { font-size: 2.25rem; }
  h2 { font-size: 1.75rem; }

  .hero h1 { font-size: 2.5rem; }

  .step-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .service-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .content-section {
    padding: var(--space-xl);
  }
}

/* Desktop */
@media (min-width: 1024px) {
  :root {
    --max-width: 900px;
  }

  .service-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .footer-content {
    flex-direction: row;
    justify-content: space-between;
    text-align: left;
  }
}

/* ================================
   SIDEBAR NAVIGATION
   ================================ */

/* Sidebar Variables */
:root {
  --sidebar-width: 280px;
  --sidebar-collapsed-width: 0px;
}

/* Layout with sidebar */
.layout-with-sidebar {
  display: flex;
  min-height: 100vh;
}

.layout-with-sidebar main {
  flex: 1;
  min-width: 0;
}

/* Sidebar Toggle Button (Mobile) */
.sidebar-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  background: transparent;
  border: none;
  cursor: pointer;
  border-radius: var(--border-radius-sm);
  transition: background var(--transition);
}

.sidebar-toggle:hover {
  background: var(--bg-secondary);
}

.sidebar-toggle svg {
  width: 24px;
  height: 24px;
  fill: var(--text-primary);
}

/* Sidebar */
.sidebar {
  position: fixed;
  top: var(--header-height);
  left: 0;
  bottom: 0;
  width: var(--sidebar-width);
  background: var(--bg-card);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  z-index: 90;
  transform: translateX(-100%);
  transition: transform 0.3s ease;
}

.sidebar.open {
  transform: translateX(0);
}

/* Sidebar Overlay (Mobile) */
.sidebar-overlay {
  display: none;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 89;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.sidebar-overlay.visible {
  display: block;
  opacity: 1;
}

/* Sidebar Content */
.sidebar-content {
  padding: var(--space-lg);
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--border);
}

.sidebar-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* Progress Summary */
.progress-summary {
  background: var(--bg-secondary);
  border-radius: var(--border-radius-sm);
  padding: var(--space-md);
  margin-bottom: var(--space-lg);
}

.progress-summary-text {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

.progress-summary-text strong {
  color: var(--text-primary);
}

.progress-summary-bar {
  height: 8px;
  background: var(--bg-primary);
  border-radius: 4px;
  overflow: hidden;
}

.progress-summary-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #22d3ee);
  border-radius: 4px;
  transition: width 0.3s ease;
}

.progress-summary-time {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: var(--space-sm);
}

/* Sidebar Navigation */
.sidebar-nav {
  list-style: none;
}

.sidebar-nav-item {
  margin-bottom: var(--space-xs);
}

.sidebar-nav-link {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--border-radius-sm);
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9rem;
  transition: all var(--transition);
}

.sidebar-nav-link:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.sidebar-nav-link.active {
  background: var(--accent-light);
  color: var(--accent);
  font-weight: 600;
}

.sidebar-nav-link.completed {
  color: var(--success);
}

.sidebar-nav-link.completed:hover {
  color: var(--success);
}

/* Step indicator in sidebar */
.sidebar-step-number {
  width: 24px;
  height: 24px;
  min-width: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--bg-secondary);
  color: var(--text-muted);
}

.sidebar-nav-link.active .sidebar-step-number {
  background: var(--accent);
  color: white;
}

.sidebar-nav-link.completed .sidebar-step-number {
  background: var(--success);
  color: white;
}

.sidebar-nav-link.completed .sidebar-step-number::after {
  content: '✓';
}

.sidebar-nav-link.completed .sidebar-step-number span {
  display: none;
}

/* Bonus step styling */
.sidebar-nav-link.bonus {
  color: var(--text-muted);
  font-style: italic;
}

.sidebar-nav-link.bonus:hover {
  color: var(--text-primary);
}

.sidebar-nav-link.bonus.active {
  color: var(--accent);
  font-style: normal;
}

.sidebar-step-number.bonus-icon {
  background: transparent;
  font-style: normal;
}

.sidebar-step-number.bonus-icon span {
  font-size: 1rem;
}

/* Sidebar Footer Links */
.sidebar-footer {
  margin-top: var(--space-xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--border);
}

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

.sidebar-footer-link {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--border-radius-sm);
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.85rem;
  transition: all var(--transition);
}

.sidebar-footer-link:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.sidebar-footer-link svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
}

/* Desktop: Sidebar always visible */
@media (min-width: 1024px) {
  .sidebar-toggle {
    display: none;
  }

  .sidebar {
    transform: translateX(0);
  }

  .sidebar-overlay {
    display: none !important;
  }

  .layout-with-sidebar main {
    margin-left: var(--sidebar-width);
  }

  .layout-with-sidebar .header {
    left: var(--sidebar-width);
  }

  .layout-with-sidebar .progress-bar {
    left: var(--sidebar-width);
  }

  :root {
    --max-width: 800px;
  }
}

/* Utilities */
.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }
.mt-lg { margin-top: var(--space-lg); }
.mb-lg { margin-bottom: var(--space-lg); }

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.fade-in {
  animation: fadeIn 0.3s ease forwards;
}

/* Focus styles for accessibility */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* Print styles */
@media print {
  .header, .progress-bar, .step-nav, .theme-toggle {
    display: none;
  }

  main {
    padding-top: 0;
  }
}