@import url('https://fonts.googleapis.com/css2?family=Google+Sans:wght@400;500;700&family=Roboto:wght@300;400;500;700&family=JetBrains+Mono:wght@400;500&display=swap');

/* Official GSoC Visual Identity System */
:root {
  /* Official GSoC Colors (matching summerofcode.withgoogle.com) */
  --google-blue: #1a73e8;
  --google-blue-hover: #1557b0;
  --google-green: #1e8e3e;
  --google-red: #d93025;
  --google-yellow: #fbbc04;
  --google-orange: #ff6d00;
  
  /* Text Colors */
  --text-primary: #202124;
  --text-secondary: #5f6368;
  --text-tertiary: #80868b;
  
  /* Surface Colors */
  --surface: #ffffff;
  --sub-surface: #f8f9fa;
  --surface-variant: #f1f3f4;
  --hairline: #dadce0;
  --border-light: #e8eaed;
  
  /* Dark Mode Palette */
  --dark-surface: #202124;
  --dark-sub-surface: #303134;
  --dark-surface-variant: #303134;
  --dark-text-primary: #e8eaed;
  --dark-text-secondary: #9aa0a6;
  --dark-text-tertiary: #5f6368;
  --dark-hairline: #5f6368;
  --dark-border-light: #5f6368;
  
  /* Typography Scale */
  --type-display: 56px;
  --type-display-lh: 64px;
  --type-h1: 40px;
  --type-h1-lh: 48px;
  --type-h2: 32px;
  --type-h2-lh: 40px;
  --type-h3: 24px;
  --type-h3-lh: 32px;
  --type-body-lg: 18px;
  --type-body-lg-lh: 28px;
  --type-body: 16px;
  --type-body-lh: 26px;
  --type-caption: 14px;
  --type-caption-lh: 20px;
  
  /* Spacing Scale */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 12px;
  --space-lg: 16px;
  --space-xl: 24px;
  --space-2xl: 32px;
  --space-3xl: 48px;
  --space-4xl: 64px;
  --space-5xl: 96px;
  
  /* Layout */
  --max-content-width: 1200px;
  --grid-gutter: 24px;
  
  /* Border Radius */
  --radius-sm: 12px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-xl: 32px;
  
  /* Shadows */
  --shadow-soft: 0 2px 8px rgba(0,0,0,0.06);
  --shadow-hover: 0 6px 24px rgba(0,0,0,0.08);
  
  /* Current theme variables (default to light) */
  --current-surface: var(--surface);
  --current-sub-surface: var(--sub-surface);
  --current-surface-variant: var(--surface-variant);
  --current-text-primary: var(--text-primary);
  --current-text-secondary: var(--text-secondary);
  --current-text-tertiary: var(--text-tertiary);
  --current-hairline: var(--hairline);
  --current-border-light: var(--border-light);
  --current-links: var(--google-blue);
}

/* Dark mode media query */
@media (prefers-color-scheme: dark) {
  :root {
    --current-surface: var(--dark-surface);
    --current-sub-surface: var(--dark-sub-surface);
    --current-surface-variant: var(--dark-surface-variant);
    --current-text-primary: var(--dark-text-primary);
    --current-text-secondary: var(--dark-text-secondary);
    --current-text-tertiary: var(--dark-text-tertiary);
    --current-hairline: var(--dark-hairline);
    --current-border-light: var(--dark-border-light);
    --current-links: var(--google-blue);
  }
}

/* Force dark mode class for testing */
.dark {
  --current-surface: var(--dark-surface);
  --current-sub-surface: var(--dark-sub-surface);
  --current-surface-variant: var(--dark-surface-variant);
  --current-text-primary: var(--dark-text-primary);
  --current-text-secondary: var(--dark-text-secondary);
  --current-text-tertiary: var(--dark-text-tertiary);
  --current-hairline: var(--dark-hairline);
  --current-border-light: var(--dark-border-light);
  --current-links: var(--google-blue);
}

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

/* Typography System - Official Google Fonts */
body {
  font-family: 'Roboto', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-size: var(--type-body);
  line-height: var(--type-body-lh);
  font-weight: 400;
  background-color: var(--current-surface);
  color: var(--current-text-primary);
  overflow-x: hidden;
  transition: background-color 0.15s ease, color 0.15s ease;
}

.type-display {
  font-family: 'Google Sans', sans-serif;
  font-size: var(--type-display);
  line-height: var(--type-display-lh);
  font-weight: 700;
  letter-spacing: -0.5px;
}

h1, .type-h1 {
  font-family: 'Google Sans', sans-serif;
  font-size: var(--type-h1);
  line-height: var(--type-h1-lh);
  font-weight: 700;
  letter-spacing: -0.5px;
  color: var(--current-text-primary);
  margin-bottom: var(--space-xl);
}

h2, .type-h2 {
  font-family: 'Google Sans', sans-serif;
  font-size: var(--type-h2);
  line-height: var(--type-h2-lh);
  font-weight: 500;
  color: var(--current-text-primary);
  margin-bottom: var(--space-xl);
}

h3, .type-h3 {
  font-family: 'Google Sans', sans-serif;
  font-size: var(--type-h3);
  line-height: var(--type-h3-lh);
  font-weight: 500;
  color: var(--current-text-primary);
  margin-bottom: var(--space-lg);
}

h4, .type-h4 {
  font-family: 'Google Sans', sans-serif;
  font-size: var(--type-body-lg);
  line-height: var(--type-body-lg-lh);
  font-weight: 500;
  color: var(--current-text-primary);
  margin-bottom: var(--space-lg);
}

.type-body-lg {
  font-size: var(--type-body-lg);
  line-height: var(--type-body-lg-lh);
  font-weight: 400;
}

.type-caption {
  font-size: var(--type-caption);
  line-height: var(--type-caption-lh);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Link Styling */
a {
  color: var(--current-links);
  text-decoration: none;
  transition: all 0.15s ease;
}

a:hover {
  text-decoration: underline;
}

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

/* Layout System */
.container {
  max-width: var(--max-content-width);
  margin: 0 auto;
  padding: 0 var(--grid-gutter);
}

.section {
  padding: 80px 0;
}

.section:nth-child(even) {
  background-color: var(--current-sub-surface);
  position: relative;
}

.section:nth-child(even)::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-image: 
    radial-gradient(circle at 100% 0%, rgba(26, 115, 232, 0.03) 0%, transparent 50%);
  pointer-events: none;
}

/* Dot pattern background for callouts */
.callout::after {
  content: '';
  position: absolute;
  top: -50px;
  right: -50px;
  width: 100px;
  height: 100px;
  background-image: radial-gradient(circle, var(--current-hairline) 1px, transparent 1px);
  background-size: 12px 12px;
  opacity: 0.3;
  z-index: 0;
}

/* Grid System */
.grid {
  display: grid;
  gap: var(--grid-gutter);
}

.grid-12 {
  grid-template-columns: repeat(12, 1fr);
}

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

/* Hero Component */
.hero {
  background: linear-gradient(135deg, var(--current-surface) 0%, var(--current-sub-surface) 100%);
  padding: 120px var(--grid-gutter);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: 
    radial-gradient(circle at 20% 50%, rgba(26, 115, 232, 0.08) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(251, 188, 4, 0.08) 0%, transparent 50%),
    radial-gradient(circle at 40% 80%, rgba(30, 142, 62, 0.06) 0%, transparent 50%);
  z-index: 1;
}

.hero * {
  position: relative;
  z-index: 2;
}

.hero-tag {
  display: inline-block;
  background: var(--google-yellow);
  color: var(--text-primary);
  padding: 6px 12px;
  border-radius: 16px;
  font-family: 'Google Sans', sans-serif;
  font-size: 14px;
  font-weight: 500;
  margin-bottom: var(--space-xl);
  letter-spacing: 0.1px;
}

.hero h1 {
  font-size: clamp(32px, 8vw, var(--type-display));
  line-height: 1.1;
  margin-bottom: var(--space-xl);
}

.hero .subtitle {
  font-size: var(--type-body-lg);
  color: var(--current-text-secondary);
  margin-bottom: var(--space-3xl);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.hero-actions {
  display: flex;
  gap: var(--space-xl);
  justify-content: center;
  flex-wrap: wrap;
}

/* Button Components - Google Material Style */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 10px 24px;
  border-radius: 4px;
  font-family: 'Google Sans', sans-serif;
  font-weight: 500;
  font-size: 14px;
  text-decoration: none;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  border: 1px solid transparent;
  min-height: 36px;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(255, 255, 255, 0.1);
  opacity: 0;
  transition: opacity 0.2s ease;
}

.btn:hover::before {
  opacity: 1;
}

.btn:hover {
  box-shadow: 0 1px 2px 0 rgba(60, 64, 67, 0.3), 0 1px 3px 1px rgba(60, 64, 67, 0.15);
}

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

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

.btn-secondary {
  background: transparent;
  color: var(--google-blue);
  border: 1px solid var(--current-hairline);
}

.btn-secondary:hover {
  background: rgba(26, 115, 232, 0.04);
  text-decoration: none;
}

/* Card Components */
.card {
  background: var(--current-surface);
  border: 1px solid var(--current-hairline);
  border-radius: var(--radius-md);
  padding: var(--space-2xl);
  transition: all 0.18s ease;
  box-shadow: var(--shadow-soft);
}

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

.card-org {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

.card-org-header {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.card-org-logo {
  width: 48px;
  height: 48px;
  border-radius: var(--space-sm);
  background: var(--current-sub-surface);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  color: var(--primary-accent);
}

.card-org h3 {
  margin: 0;
}

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

.tag {
  background: var(--current-surface-variant);
  color: var(--current-text-secondary);
  padding: 4px 12px;
  border-radius: 16px;
  font-family: 'Google Sans', sans-serif;
  font-size: 12px;
  font-weight: 500;
  text-transform: none;
  letter-spacing: 0.1px;
  border: 1px solid var(--current-hairline);
}

.tag-beginner {
  background: rgba(30, 142, 62, 0.1);
  color: var(--google-green);
  border-color: rgba(30, 142, 62, 0.2);
}

.tag-ml {
  background: rgba(251, 188, 4, 0.1);
  color: #ea8600;
  border-color: rgba(251, 188, 4, 0.2);
}

/* Timeline/Stepper Component */
.timeline {
  display: flex;
  justify-content: space-between;
  margin: var(--space-4xl) 0;
  padding: var(--space-2xl);
  background: var(--current-sub-surface);
  border-radius: var(--radius-md);
  position: relative;
}

.timeline::before {
  content: '';
  position: absolute;
  top: 50%;
  left: var(--space-2xl);
  right: var(--space-2xl);
  height: 2px;
  background: var(--current-hairline);
  z-index: 1;
}

.timeline-step {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  position: relative;
  flex: 1;
  z-index: 2;
}

.timeline-step-icon {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--current-surface);
  border: 3px solid var(--current-hairline);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-lg);
  font-weight: 600;
  color: var(--current-text-secondary);
}

.timeline-step.active .timeline-step-icon {
  background: var(--google-blue);
  border-color: var(--google-blue);
  color: white;
}

.timeline-step.completed .timeline-step-icon {
  background: var(--google-green);
  border-color: var(--google-green);
  color: white;
}

.timeline-step h4 {
  font-size: var(--type-body);
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--current-text-primary);
}

.timeline-step p {
  font-size: var(--type-caption);
  color: var(--current-text-secondary);
  max-width: 120px;
}

/* Stats Component */
.stats {
  display: flex;
  justify-content: center;
  gap: var(--space-4xl);
  margin: var(--space-4xl) 0;
}

.stat {
  text-align: center;
}

.stat-number {
  font-family: 'Google Sans', sans-serif;
  font-size: var(--type-h1);
  font-weight: 700;
  color: var(--google-blue);
  display: block;
  margin-bottom: var(--space-sm);
}

.stat-label {
  font-size: var(--type-body);
  color: var(--current-text-secondary);
}

/* FAQ Accordion */
.faq-item {
  border-bottom: 1px solid var(--current-hairline);
}

.faq-question {
  width: 100%;
  padding: var(--space-xl);
  background: none;
  border: none;
  text-align: left;
  font-family: inherit;
  font-size: var(--type-body);
  font-weight: 600;
  color: var(--current-text-primary);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all 0.15s ease;
}

.faq-question:hover {
  color: var(--current-links);
}

.faq-icon {
  transition: transform 0.2s ease;
}

.faq-question[aria-expanded="true"] .faq-icon {
  transform: rotate(180deg);
}

.faq-answer {
  padding: 0 var(--space-xl) var(--space-xl);
  color: var(--current-text-secondary);
  overflow: hidden;
  transition: max-height 0.2s ease;
}

/* Callout Component */
.callout {
  background: linear-gradient(135deg, rgba(249, 171, 0, 0.05) 0%, var(--current-surface) 100%);
  border: 1px solid rgba(249, 171, 0, 0.2);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  margin: var(--space-2xl) 0;
  position: relative;
  overflow: hidden;
}

.callout::before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  width: 200px;
  height: 200px;
  background: radial-gradient(circle, rgba(249, 171, 0, 0.1) 0%, transparent 70%);
  border-radius: 50%;
  transform: translate(50%, -50%);
}

.callout * {
  position: relative;
  z-index: 1;
}

/* Footer Component */
footer {
  background: var(--current-sub-surface);
  border-top: 1px solid var(--current-hairline);
  padding: var(--space-4xl) var(--grid-gutter);
  margin-top: var(--space-5xl);
}

.footer-content {
  max-width: var(--max-content-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-2xl);
}

.footer-section h4 {
  font-size: var(--type-body);
  font-weight: 600;
  color: var(--current-text-primary);
  margin-bottom: var(--space-lg);
}

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

.footer-section li {
  margin-bottom: var(--space-sm);
}

.footer-section a {
  color: var(--current-text-secondary);
  font-size: var(--type-caption);
}

.footer-section a:hover {
  color: var(--current-links);
}

/* Header & Navigation */
header {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--current-hairline);
  padding: var(--space-lg) 0;
  position: sticky;
  top: 0;
  z-index: 1000;
  transition: background-color 0.15s ease;
}

@media (prefers-color-scheme: dark) {
  header {
    background: rgba(18, 18, 18, 0.95);
  }
}

nav {
  max-width: var(--max-content-width);
  margin: 0 auto;
  padding: 0 var(--grid-gutter);
}

nav ul {
  list-style: none;
  display: flex;
  justify-content: center;
  gap: var(--space-sm);
  flex-wrap: wrap;
}

nav a {
  padding: var(--space-md) var(--space-lg);
  border-radius: var(--space-sm);
  font-weight: 500;
  font-size: var(--type-caption);
  text-transform: none;
  letter-spacing: normal;
  transition: all 0.12s ease;
}

nav a:hover {
  background-color: var(--current-sub-surface);
  text-decoration: none;
  transform: scale(1.01);
}

/* Main Content Container */
main {
  background-color: var(--current-surface);
  transition: background-color 0.15s ease;
}

/* Responsive Design */
@media (max-width: 768px) {
  .hero {
    padding: var(--space-4xl) var(--space-xl);
  }
  
  .hero-actions {
    flex-direction: column;
    align-items: center;
  }
  
  .timeline {
    flex-direction: column;
    gap: var(--space-2xl);
  }
  
  .timeline::before {
    display: none;
  }
  
  .stats {
    flex-direction: column;
    gap: var(--space-2xl);
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  nav ul {
    justify-content: flex-start;
    overflow-x: auto;
    padding-bottom: var(--space-sm);
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-lg);
  }
  
  .section {
    padding: var(--space-4xl) 0;
  }
  
  .card {
    padding: var(--space-xl);
  }
}

/* Smooth scrolling and animations */
html {
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  
  html {
    scroll-behavior: auto;
  }
}

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

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

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mb-0 { margin-bottom: 0; }
.mb-xs { margin-bottom: var(--space-xs); }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }
.mb-2xl { margin-bottom: var(--space-2xl); }
.mb-3xl { margin-bottom: var(--space-3xl); }
.mb-4xl { margin-bottom: var(--space-4xl); }
.mb-5xl { margin-bottom: var(--space-5xl); }