/* ===== VARIABLES CSS ===== */
:root {
  /* Couleurs primaires */
  --color-primary-50: hsl(210, 40%, 98%);
  --color-primary-100: hsl(210, 40%, 96%);
  --color-primary-200: hsl(214, 32%, 91%);
  --color-primary-300: hsl(213, 27%, 84%);
  --color-primary-400: hsl(215, 20%, 65%);
  --color-primary-500: hsl(215, 16%, 47%);
  --color-primary-600: hsl(215, 19%, 35%);
  --color-primary-700: hsl(215, 25%, 27%);
  --color-primary-800: hsl(217, 33%, 17%);
  --color-primary-900: hsl(222, 47%, 11%);
  --color-primary-950: hsl(229, 84%, 5%);

  /* Couleurs d'accent (vert scientifique) */
  --color-accent-50: hsl(138, 76%, 97%);
  --color-accent-100: hsl(141, 84%, 93%);
  --color-accent-200: hsl(141, 79%, 85%);
  --color-accent-300: hsl(142, 77%, 73%);
  --color-accent-400: hsl(142, 69%, 58%);
  --color-accent-500: hsl(142, 71%, 45%);
  --color-accent-600: hsl(142, 76%, 36%);
  --color-accent-700: hsl(142, 72%, 29%);
  --color-accent-800: hsl(143, 64%, 24%);
  --color-accent-900: hsl(144, 61%, 20%);
  --color-accent-950: hsl(145, 80%, 10%);

  /* Couleurs sémantiques */
  --color-background: var(--color-primary-50);
  --color-foreground: var(--color-primary-900);
  --color-card: white;
  --color-border: var(--color-primary-200);
  --color-muted: var(--color-primary-100);
  --color-muted-foreground: var(--color-primary-500);

  /* Typographie */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;
  
  /* Espacements */
  --spacing-1: 0.25rem;
  --spacing-2: 0.5rem;
  --spacing-3: 0.75rem;
  --spacing-4: 1rem;
  --spacing-5: 1.25rem;
  --spacing-6: 1.5rem;
  --spacing-8: 2rem;
  --spacing-10: 2.5rem;
  --spacing-12: 3rem;
  --spacing-16: 4rem;
  --spacing-20: 5rem;
  --spacing-24: 6rem;

  /* Bordures */
  --radius-sm: 0.125rem;
  --radius: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;

  /* Ombres */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

  /* Animations */
  --transition: all 0.2s ease-in-out;
  --transition-slow: all 0.3s ease-in-out;
}

/* Mode sombre */
[data-theme="dark"] {
  --color-background: var(--color-primary-950);
  --color-foreground: var(--color-primary-50);
  --color-card: var(--color-primary-900);
  --color-border: var(--color-primary-700);
  --color-muted: var(--color-primary-800);
  --color-muted-foreground: var(--color-primary-400);
}

/* ===== RESET & BASE STYLES ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 6rem;
}

body {
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-foreground);
  background-color: var(--color-background);
  transition: var(--transition);
}

/* ===== TYPOGRAPHIE ===== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--spacing-4);
  color: var(--color-foreground);
}

h1 {
  font-size: 2.5rem;
  letter-spacing: -0.025em;
}

h2 {
  font-size: 2rem;
  letter-spacing: -0.02em;
}

h3 {
  font-size: 1.5rem;
  letter-spacing: -0.015em;
}

p {
  margin-bottom: var(--spacing-4);
}

/* ===== LAYOUT ===== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-4);
}

/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: var(--color-card);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  backdrop-filter: blur(8px);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-4) var(--spacing-6);
  max-width: 1200px;
  margin: 0 auto;
}

.nav-brand h1 {
  margin: 0;
  font-size: 1.5rem;
  color: var(--color-accent-600);
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--spacing-6);
}

.nav-menu a {
  text-decoration: none;
  color: var(--color-foreground);
  font-weight: 500;
  transition: var(--transition);
}

.nav-menu a:hover {
  color: var(--color-accent-600);
}

/* Hero Section */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: var(--spacing-20) var(--spacing-6) var(--spacing-12);
  background: linear-gradient(135deg, var(--color-accent-50) 0%, var(--color-primary-100) 100%);
  position: relative;
  overflow: hidden;
}

[data-theme="dark"] .hero {
  background: linear-gradient(135deg, var(--color-primary-900) 0%, var(--color-primary-800) 100%);
}

.hero-content {
  max-width: 600px;
  z-index: 2;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--color-muted-foreground);
  margin-bottom: var(--spacing-8);
}

.hero-actions {
  display: flex;
  gap: var(--spacing-4);
  flex-wrap: wrap;
}

/* Main Sections */
.main {
  padding-top: var(--spacing-16);
}

.section {
  padding: var(--spacing-16) 0;
  scroll-margin-top: 6rem;
}

.section:not(:last-child) {
  border-bottom: 1px solid var(--color-border);
}

/* Grid System */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--spacing-6);
  margin-top: var(--spacing-6);
}

/* Cards */
.card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--spacing-6);
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
}

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

.card-header {
  margin-bottom: var(--spacing-4);
}

.card-title {
  font-size: 1.25rem;
  margin-bottom: var(--spacing-2);
  color: var(--color-accent-700);
}

.card-subtitle {
  color: var(--color-muted-foreground);
  font-size: 0.875rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-3) var(--spacing-6);
  border-radius: var(--radius);
  font-weight: 500;
  text-decoration: none;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  font-size: 0.875rem;
  line-height: 1;
}

.btn-primary {
  background: var(--color-accent-600);
  color: white;
}

.btn-primary:hover {
  background: var(--color-accent-700);
  transform: translateY(-1px);
}

.btn-secondary {
  background: transparent;
  color: var(--color-accent-600);
  border: 1px solid var(--color-accent-300);
}

.btn-secondary:hover {
  background: var(--color-accent-50);
  border-color: var(--color-accent-400);
}

.btn-icon {
  padding: var(--spacing-2);
  border-radius: var(--radius);
  background: transparent;
  border: none;
  cursor: pointer;
  transition: var(--transition);
}

.btn-icon:hover {
  background: var(--color-muted);
}

/* Forms */
.input {
  padding: var(--spacing-3) var(--spacing-4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-card);
  color: var(--color-foreground);
  font-size: 0.875rem;
  transition: var(--transition);
}

.input:focus {
  outline: none;
  border-color: var(--color-accent-400);
  box-shadow: 0 0 0 3px rgb(142 71 186 / 0.1);
}

/* Modal */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  opacity: 0;
  visibility: hidden;
  transition: var(--transition-slow);
}

.modal[aria-hidden="false"] {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background: var(--color-card);
  border-radius: var(--radius-xl);
  padding: var(--spacing-6);
  max-width: 600px;
  width: 90%;
  max-height: 80vh;
  overflow-y: auto;
  position: relative;
  box-shadow: var(--shadow-xl);
}

.modal-close {
  position: absolute;
  top: var(--spacing-4);
  right: var(--spacing-4);
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--color-muted-foreground);
}

/* Footer */
.footer {
  background: var(--color-muted);
  padding: var(--spacing-12) 0;
  margin-top: var(--spacing-16);
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-6);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-8);
}

.footer-section h3 {
  color: var(--color-accent-700);
  margin-bottom: var(--spacing-4);
}

/* 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-muted {
  color: var(--color-muted-foreground);
}

.mb-4 {
  margin-bottom: var(--spacing-4);
}

.mt-6 {
  margin-top: var(--spacing-6);
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-menu {
    display: none;
  }
  
  .hero {
    padding: var(--spacing-16) var(--spacing-4) var(--spacing-8);
  }
  
  .hero-content {
    text-align: center;
  }
  
  .hero-actions {
    justify-content: center;
  }
  
  .grid {
    grid-template-columns: 1fr;
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  h2 {
    font-size: 1.5rem;
  }
}

@media (max-width: 480px) {
  .nav {
    padding: var(--spacing-3);
  }
  
  .section {
    padding: var(--spacing-8) 0;
  }
  
  .card {
    padding: var(--spacing-4);
  }
}

/* Animation keyframes */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideIn {
  from {
    transform: translateX(-100%);
  }
  to {
    transform: translateX(0);
  }
}

/* Reduced motion support */
@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 */
button:focus-visible,
a:focus-visible,
input:focus-visible {
  outline: 2px solid var(--color-accent-500);
  outline-offset: 2px;
}

/* Print styles */
@media print {
  .header,
  .footer,
  .hero-actions {
    display: none !important;
  }
  
  body {
    color: black;
    background: white;
  }
  
  .card {
    break-inside: avoid;
    border: 1px solid #ccc;
  }
}