:root {
  /* Core Color Palette */
  --bg-color: #ffffff;
  --text-color: #171717;
  --primary: #2A7D4E;
  --secondary: #A3D9A5;
  
  /* Extended Colors for UI & Contrast */
  --primary-dark: #1e5c38;
  --secondary-light: #e6f4e7;
  --text-muted: #4a4a4a;
  --border-color: #d1d5db;
  --focus-ring: rgba(163, 217, 165, 0.6);
  
  /* Typography */
  --font-sans: 'Inter', 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  
  /* Structure & Effects */
  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --transition-fast: 0.2s ease-in-out;
  --transition-smooth: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Base Styles & Texture */
body {
  margin: 0;
  padding: 0;
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: var(--font-sans);
  font-size: 1.125rem; /* 18px for better readability */
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  
  /* Subtle light grain texture for tactile feel */
  background-image: url('data:image/svg+xml;utf8,%3Csvg viewBox="0 0 200 200" xmlns="http://www.w3.org/2000/svg"%3E%3Cfilter id="noiseFilter"%3E%3CfeTurbulence type="fractalNoise" baseFrequency="0.8" numOctaves="3" stitchTiles="stitch"/%3E%3C/filter%3E%3Crect width="100%25" height="100%25" filter="url(%23noiseFilter)" opacity="0.04"/%3E%3C/svg%3E');
}

/* Typography Hierarchy */
h1, h2, h3, h4 {
  color: var(--text-color);
  line-height: 1.2;
  margin-top: 0;
  margin-bottom: 1rem;
  font-weight: 700;
}

h1 {
  font-size: 2.5rem;
  letter-spacing: -0.02em;
}

h2 {
  font-size: 2rem;
  color: var(--primary);
}

h3 {
  font-size: 1.5rem;
}

p {
  margin-top: 0;
  margin-bottom: 1.5rem;
}

/* Links */
a {
  color: var(--primary);
  text-decoration: underline;
  text-decoration-thickness: 2px;
  text-underline-offset: 4px;
  transition: all var(--transition-fast);
  font-weight: 600;
  border-radius: 4px;
}

a:hover, a:focus {
  color: var(--primary-dark);
  background-color: var(--secondary-light);
  text-decoration-color: transparent;
}

/* Layout: Asymmetric Grid */
.layout-container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 2rem;
  display: grid;
  gap: 3rem;
  grid-template-columns: 1fr;
}

@media (min-width: 992px) {
  .layout-container {
    /* Asymmetric grid: Main content wider than sidebar */
    grid-template-columns: 8fr 4fr;
  }
  
  .header-full {
    grid-column: 1 / -1;
  }
}

/* Header */
.site-header {
  padding: 2rem 0;
  border-bottom: 2px solid var(--secondary-light);
  margin-bottom: 2rem;
  position: relative;
  z-index: 100;
}

.site-header .logo-area {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* Navigation & Multi-level Dropdowns */
nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
}

nav li {
  position: relative;
}

nav a {
  display: block;
  padding: 0.5rem 1rem;
  text-decoration: none;
  color: var(--text-color);
  font-weight: 600;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

nav a:hover,
nav a:focus {
  background-color: var(--secondary-light);
  color: var(--primary-dark);
}

/* First-level dropdown */
nav li ul {
  position: absolute;
  top: 100%;
  left: 0;
  flex-direction: column;
  background-color: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
  min-width: 240px;
  padding: 0.5rem 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
  z-index: 100;
}

nav li:hover > ul,
nav li:focus-within > ul {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

nav li ul li {
  width: 100%;
}

nav li ul a {
  padding: 0.75rem 1.5rem;
  border-radius: 0;
  font-weight: 400;
}

/* Nested dropdowns (Level 3+) */
nav li ul ul {
  top: 0;
  left: 100%;
  transform: translateX(10px);
}

nav li ul li:hover > ul,
nav li ul li:focus-within > ul {
  transform: translateX(0);
}

/* Responsive adjustment for dropdowns */
@media (max-width: 991px) {
  nav ul {
    flex-direction: column;
    align-items: stretch;
  }
  nav li {
    width: 100%;
  }
  nav li ul {
    position: static;
    box-shadow: none;
    border: none;
    border-left: 2px solid var(--secondary-light);
    border-radius: 0;
    margin-left: 1rem;
    padding-left: 0.5rem;
    opacity: 1;
    visibility: visible;
    transform: none;
    display: none;
    min-width: auto;
  }
  nav li:hover > ul,
  nav li:focus-within > ul {
    display: flex;
  }
  nav li ul ul {
    margin-left: 1rem;
    left: auto;
    top: auto;
    transform: none;
  }
  nav li ul li:hover > ul,
  nav li ul li:focus-within > ul {
    transform: none;
  }
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  background-color: var(--primary);
  color: var(--bg-color);
  font-family: var(--font-sans);
  font-size: 1.125rem;
  font-weight: 600;
  padding: 1rem 2rem;
  border: 2px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition-fast);
  box-shadow: 0 4px 6px rgba(42, 125, 78, 0.15);
}

.btn:hover {
  background-color: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 6px 12px rgba(42, 125, 78, 0.25);
}

.btn-secondary {
  background-color: var(--secondary);
  color: var(--text-color);
  box-shadow: none;
}

.btn-secondary:hover {
  background-color: #8cc98e;
  box-shadow: 0 4px 6px rgba(163, 217, 165, 0.4);
}

/* Focus Accessibility */
*:focus-visible {
  outline: 4px solid var(--primary);
  outline-offset: 4px;
  border-radius: 2px;
}

/* Cards (Fiches explicatives) */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.card {
  background-color: var(--bg-color);
  border: 2px solid var(--secondary-light);
  border-radius: var(--radius-md);
  padding: 2rem;
  position: relative;
  transition: var(--transition-smooth);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.02);
}

.card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 6px;
  background-color: var(--secondary);
  border-radius: var(--radius-md) var(--radius-md) 0 0;
  transition: background-color var(--transition-fast);
}

.card:hover {
  border-color: var(--secondary);
  transform: translateY(-4px);
  box-shadow: 0 12px 24px rgba(42, 125, 78, 0.08);
}

.card:hover::before {
  background-color: var(--primary);
}

.card-icon {
  width: 48px;
  height: 48px;
  background-color: var(--secondary-light);
  color: var(--primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.5rem;
  font-size: 1.5rem;
}

/* Interactive Calculator (Simulateur) */
.calculator-wrapper {
  background-color: #fdfdfd;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 3rem;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
  margin-bottom: 3rem;
  position: relative;
  overflow: hidden;
}

.calculator-progress {
  display: flex;
  align-items: center;
  margin-bottom: 2.5rem;
  gap: 0.5rem;
}

.progress-bar {
  flex-grow: 1;
  height: 8px;
  background-color: var(--secondary-light);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background-color: var(--primary);
  width: 33%; /* Example width */
  transition: width var(--transition-smooth);
}

/* Form Elements */
.form-group {
  margin-bottom: 2rem;
  animation: slideIn 0.5s ease forwards;
}

label {
  display: block;
  font-weight: 700;
  margin-bottom: 0.75rem;
  font-size: 1.125rem;
}

.helper-text {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
  display: block;
}

input[type="text"],
input[type="number"],
select {
  width: 100%;
  padding: 1.25rem;
  font-family: var(--font-sans);
  font-size: 1.125rem;
  color: var(--text-color);
  background-color: var(--bg-color);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  box-sizing: border-box;
}

input:hover, select:hover {
  border-color: var(--secondary);
}

input:focus, select:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 4px var(--focus-ring);
  outline: none;
}

/* Radio & Checkbox Cards (Accessible and touch-friendly) */
.options-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
}

.option-card {
  position: relative;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  gap: 1rem;
}

.option-card:hover {
  border-color: var(--secondary);
  background-color: var(--secondary-light);
}

.option-card input[type="radio"],
.option-card input[type="checkbox"] {
  width: 24px;
  height: 24px;
  accent-color: var(--primary);
  cursor: pointer;
}

.option-card:has(input:checked) {
  border-color: var(--primary);
  background-color: var(--secondary-light);
  box-shadow: 0 4px 10px rgba(42, 125, 78, 0.1);
}

.option-card:has(input:focus-visible) {
  outline: 4px solid var(--primary);
  outline-offset: 2px;
}

/* Calculator Animations */
@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.step-transition {
  transition: opacity 0.4s ease, transform 0.4s ease;
}

.step-hidden {
  opacity: 0;
  transform: translateX(30px);
  pointer-events: none;
  position: absolute;
  visibility: hidden;
}

.step-active {
  opacity: 1;
  transform: translateX(0);
  position: relative;
  visibility: visible;
}

/* Sidebar / Guide des démarches */
.sidebar {
  background-color: var(--secondary-light);
  border-radius: var(--radius-md);
  padding: 2.5rem;
  height: fit-content;
}

.sidebar-step {
  display: flex;
  gap: 1rem;
  margin-bottom: 2rem;
  position: relative;
}

.sidebar-step:not(:last-child)::after {
  content: '';
  position: absolute;
  top: 40px;
  left: 19px;
  width: 2px;
  height: calc(100% - 20px);
  background-color: var(--secondary);
}

.step-number {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  background-color: var(--bg-color);
  color: var(--primary);
  border: 2px solid var(--primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.25rem;
  z-index: 2;
}

/* Notices & Alerts */
.alert-info {
  background-color: #f0f7f1;
  border-left: 6px solid var(--primary);
  padding: 1.5rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  display: flex;
  gap: 1rem;
  align-items: flex-start;
  margin: 2rem 0;
}

.alert-icon {
  color: var(--primary);
  font-size: 1.5rem;
}

/* Footer */
.site-footer {
  background-color: var(--text-color);
  color: var(--bg-color);
  padding: 4rem 2rem;
  margin-top: 4rem;
  text-align: center;
}

.site-footer a {
  color: var(--secondary);
  text-decoration: none;
}

.site-footer a:hover,
.site-footer a:focus {
  color: var(--bg-color);
  background-color: var(--primary);
}