/* ═══════════════════════════════════════════════════════════
   SKILL UP v2 — Design System
   Mobile-First | Responsive | WCAG AA | Institutionnel
   ═══════════════════════════════════════════════════════════ */

/* ── CSS Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body { -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }
img, picture, video, canvas, svg { display: block; max-width: 100%; }
input, button, textarea, select { font: inherit; }

/* ── Custom Properties (Light Theme) ── */
:root {
  /* Palette */
  --color-primary: #1A3C6E;
  --color-primary-light: #2A5A9E;
  --color-primary-dark: #0F2544;
  --color-secondary: #2E7D32;
  --color-secondary-light: #43A047;
  --color-accent: #F57C00;
  --color-accent-light: #FF9800;

  /* Backgrounds */
  --bg-body: #F5F7FA;
  --bg-surface: #FFFFFF;
  --bg-surface-hover: #F0F2F5;
  --bg-elevated: #FFFFFF;

  /* Text */
  --text-primary: #1C1C2E;
  --text-secondary: #5A6478;
  --text-muted: #8E95A5;
  --text-inverse: #FFFFFF;

  /* Borders */
  --border-color: #E2E8F0;
  --border-focus: #1A3C6E;

  /* Status */
  --color-success: #43A047;
  --color-error: #E53935;
  --color-warning: #F57C00;
  --color-info: #0288D1;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(26,60,110,0.06);
  --shadow-md: 0 4px 12px rgba(26,60,110,0.1);
  --shadow-lg: 0 12px 32px rgba(26,60,110,0.15);
  --shadow-xl: 0 20px 48px rgba(26,60,110,0.2);

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;

  /* Radii */
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;

  /* Typography */
  --font-heading: 'Merriweather', 'Georgia', serif;
  --font-body: 'Source Sans Pro', 'Lato', -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Transitions */
  --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.3s cubic-bezier(0.4, 0, 0.2, 1);

  /* Z-index */
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-overlay: 300;
  --z-modal: 400;
  --z-toast: 500;

  /* Layout */
  --sidebar-width: 260px;
  --header-height: 56px;
  --max-content: 1280px;
}

/* ── Dark Mode ── */
@media (prefers-color-scheme: dark) {
  :root {
    --bg-body: #0D1B2A;
    --bg-surface: #1B2838;
    --bg-surface-hover: #243447;
    --bg-elevated: #213345;
    --text-primary: #E8ECF1;
    --text-secondary: #A0ADBF;
    --text-muted: #6B7B8F;
    --border-color: #2D3E50;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
    --shadow-lg: 0 12px 32px rgba(0,0,0,0.4);
  }
}

/* ── Body ── */
body {
  font-family: var(--font-body);
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-body);
  min-height: 100vh;
}

/* ── Typography — Mobile First ── */
h1, h2, h3, h4, h5, h6 { font-family: var(--font-heading); font-weight: 700; line-height: 1.3; color: var(--text-primary); }
h1 { font-size: 24px; margin-bottom: var(--space-lg); }
h2 { font-size: 20px; margin-bottom: var(--space-md); }
h3 { font-size: 18px; margin-bottom: var(--space-sm); }
h4 { font-size: 16px; }
p { margin-bottom: var(--space-md); color: var(--text-secondary); }
small { font-size: 12px; color: var(--text-muted); }

@media (min-width: 768px) {
  body { font-size: 15px; }
  h1 { font-size: 30px; }
  h2 { font-size: 24px; }
  h3 { font-size: 20px; }
}

@media (min-width: 1024px) {
  body { font-size: 16px; }
  h1 { font-size: 40px; }
  h2 { font-size: 32px; }
  h3 { font-size: 24px; }
}

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

.app-main {
  flex: 1;
  padding: var(--space-md);
  max-width: 100%;
  overflow-x: hidden;
}

@media (min-width: 768px) {
  .app-main { padding: var(--space-lg); }
}

@media (min-width: 1024px) {
  .app-main { padding: var(--space-xl); margin-left: var(--sidebar-width); }
}

.container { max-width: var(--max-content); margin: 0 auto; width: 100%; }

/* Grid system */
.grid { display: grid; gap: var(--space-md); }
.grid-2 { grid-template-columns: 1fr; }
.grid-3 { grid-template-columns: 1fr; }
.grid-4 { grid-template-columns: 1fr; }

@media (min-width: 768px) {
  .grid-2 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid { gap: var(--space-lg); }
}

@media (min-width: 1024px) {
  .grid-3 { grid-template-columns: repeat(3, 1fr); }
  .grid-4 { grid-template-columns: repeat(3, 1fr); }
}

@media (min-width: 1280px) {
  .grid-4 { grid-template-columns: repeat(4, 1fr); }
}

/* ── Header ── */
.app-header {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  height: var(--header-height);
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  padding: 0 var(--space-md);
  box-shadow: var(--shadow-sm);
}

@media (min-width: 1024px) {
  .app-header { padding: 0 var(--space-xl); margin-left: var(--sidebar-width); }
}

.header-title {
  font-family: var(--font-heading);
  font-size: 18px;
  font-weight: 700;
  color: var(--color-primary);
}

.header-actions { margin-left: auto; display: flex; align-items: center; gap: var(--space-sm); }

/* ── Sidebar ── */
.sidebar {
  position: fixed;
  top: 0;
  left: -280px;
  width: 280px;
  height: 100vh;
  background: var(--color-primary-dark);
  color: var(--text-inverse);
  z-index: var(--z-overlay);
  transition: left var(--transition-slow);
  overflow-y: auto;
  display: flex;
  flex-direction: column;
}

.sidebar.open { left: 0; }

.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: calc(var(--z-overlay) - 1);
}

.sidebar.open ~ .sidebar-overlay { display: block; }

@media (min-width: 1024px) {
  .sidebar {
    left: 0;
    width: var(--sidebar-width);
  }
  .sidebar-overlay { display: none !important; }
  .menu-toggle { display: none !important; }
}

.sidebar-brand {
  padding: var(--space-lg);
  border-bottom: 1px solid rgba(255,255,255,0.1);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.sidebar-brand h2 {
  font-size: 20px;
  color: #FFFFFF;
  margin: 0;
}

.sidebar-nav { flex: 1; padding: var(--space-md) 0; }

.nav-section { padding: var(--space-xs) var(--space-md); margin-top: var(--space-md); }
.nav-section-title { font-size: 11px; text-transform: uppercase; letter-spacing: 1px; color: rgba(255,255,255,0.4); font-family: var(--font-body); font-weight: 600; }

.nav-item {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 10px var(--space-lg);
  color: rgba(255,255,255,0.7);
  text-decoration: none;
  font-size: 14px;
  transition: all var(--transition-fast);
  border-left: 3px solid transparent;
  cursor: pointer;
  min-height: 48px;
}

.nav-item:hover { background: rgba(255,255,255,0.08); color: #FFFFFF; }
.nav-item.active { background: rgba(255,255,255,0.12); color: #FFFFFF; border-left-color: var(--color-accent); }

.nav-item svg { width: 20px; height: 20px; flex-shrink: 0; }
.nav-badge { margin-left: auto; background: var(--color-accent); color: #FFF; font-size: 11px; padding: 2px 7px; border-radius: var(--radius-full); font-weight: 600; }

/* ── Cards ── */
.card {
  background: var(--bg-surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  padding: var(--space-lg);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

@media (prefers-reduced-motion: reduce) {
  .card:hover { transform: none; }
}

.card-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: var(--space-md); }
.card-title { font-family: var(--font-heading); font-size: 16px; font-weight: 700; }
.card-body { color: var(--text-secondary); }
.card-footer { margin-top: var(--space-md); padding-top: var(--space-md); border-top: 1px solid var(--border-color); }

/* Stat cards */
.stat-card { text-align: center; }
.stat-value { font-size: 32px; font-weight: 700; color: var(--color-primary); font-family: var(--font-heading); }
.stat-label { font-size: 13px; color: var(--text-muted); margin-top: var(--space-xs); }
.stat-change { font-size: 12px; font-weight: 600; margin-top: var(--space-xs); }
.stat-change.positive { color: var(--color-success); }
.stat-change.negative { color: var(--color-error); }

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: 10px var(--space-lg);
  font-size: 14px;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  min-height: 48px;
  width: 100%;
  text-decoration: none;
  line-height: 1;
}

@media (min-width: 768px) {
  .btn { width: auto; min-height: 44px; }
}

.btn:focus-visible { outline: 2px solid var(--border-focus); outline-offset: 2px; }

.btn-primary { background: var(--color-primary); color: #FFF; }
.btn-primary:hover { background: var(--color-primary-light); }

.btn-secondary { background: var(--bg-surface); color: var(--text-primary); border: 1px solid var(--border-color); }
.btn-secondary:hover { background: var(--bg-surface-hover); }

.btn-accent { background: var(--color-accent); color: #FFF; }
.btn-accent:hover { background: var(--color-accent-light); }

.btn-success { background: var(--color-success); color: #FFF; }
.btn-danger { background: var(--color-error); color: #FFF; }

.btn-ghost { background: transparent; color: var(--text-secondary); }
.btn-ghost:hover { background: var(--bg-surface-hover); }

.btn-sm { padding: 6px var(--space-md); font-size: 13px; min-height: 36px; }
.btn-lg { padding: 14px var(--space-xl); font-size: 16px; }

.btn-icon { width: 44px; height: 44px; padding: 0; border-radius: var(--radius-md); }

/* ── Forms ── */
.form-group { margin-bottom: var(--space-md); }

.form-label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-xs);
}

.form-input {
  width: 100%;
  padding: 10px 14px;
  font-size: 14px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-surface);
  color: var(--text-primary);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  min-height: 48px;
}

.form-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(26,60,110,0.15);
}

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

textarea.form-input { min-height: 100px; resize: vertical; }

select.form-input { appearance: none; background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%235A6478' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E"); background-repeat: no-repeat; background-position: right 12px center; padding-right: 40px; }

.form-error { font-size: 12px; color: var(--color-error); margin-top: var(--space-xs); }

/* ── Tables ── */
.table-wrapper { overflow-x: auto; -webkit-overflow-scrolling: touch; border-radius: var(--radius-lg); border: 1px solid var(--border-color); }

table { width: 100%; border-collapse: collapse; background: var(--bg-surface); }
th { font-size: 12px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.5px; color: var(--text-muted); text-align: left; padding: 12px 16px; border-bottom: 1px solid var(--border-color); background: var(--bg-surface-hover); white-space: nowrap; }
td { padding: 12px 16px; border-bottom: 1px solid var(--border-color); font-size: 14px; }
tr:last-child td { border-bottom: none; }
tr:hover td { background: var(--bg-surface-hover); }

/* Mobile: transform table to cards */
@media (max-width: 767px) {
  .table-responsive thead { display: none; }
  .table-responsive tbody tr {
    display: block;
    margin-bottom: var(--space-sm);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--space-md);
  }
  .table-responsive tbody td {
    display: flex;
    justify-content: space-between;
    padding: 6px 0;
    border: none;
  }
  .table-responsive tbody td::before {
    content: attr(data-label);
    font-weight: 600;
    font-size: 12px;
    color: var(--text-muted);
  }
}

/* ── Badges / Tags ── */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 3px 10px;
  font-size: 12px;
  font-weight: 600;
  border-radius: var(--radius-full);
  line-height: 1.4;
}

.badge-primary { background: rgba(26,60,110,0.1); color: var(--color-primary); }
.badge-success { background: rgba(67,160,71,0.1); color: var(--color-success); }
.badge-warning { background: rgba(245,124,0,0.1); color: var(--color-warning); }
.badge-danger { background: rgba(229,57,53,0.1); color: var(--color-error); }
.badge-info { background: rgba(2,136,209,0.1); color: var(--color-info); }

/* ── Avatar ── */
.avatar {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  object-fit: cover;
  background: var(--color-primary);
  color: #FFF;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 16px;
  flex-shrink: 0;
}

.avatar-sm { width: 32px; height: 32px; font-size: 13px; }
.avatar-lg { width: 56px; height: 56px; font-size: 22px; }

/* ── Progress Bar ── */
.progress { height: 8px; background: var(--border-color); border-radius: var(--radius-full); overflow: hidden; }
.progress-fill { height: 100%; border-radius: var(--radius-full); transition: width var(--transition-slow); }
.progress-fill.primary { background: var(--color-primary); }
.progress-fill.success { background: var(--color-success); }
.progress-fill.warning { background: var(--color-warning); }
.progress-fill.danger { background: var(--color-error); }

/* ── Toast Notifications ── */
.toast-container {
  position: fixed;
  top: var(--space-lg);
  right: var(--space-md);
  z-index: var(--z-toast);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  max-width: 400px;
  width: calc(100% - 32px);
}

.toast {
  padding: var(--space-md);
  border-radius: var(--radius-md);
  background: var(--bg-elevated);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: flex-start;
  gap: var(--space-sm);
  animation: fadeInUp 0.3s ease-out;
}

.toast-success { border-left: 4px solid var(--color-success); }
.toast-error { border-left: 4px solid var(--color-error); }
.toast-info { border-left: 4px solid var(--color-info); }

/* ── Modal ── */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: var(--z-modal);
  display: flex;
  align-items: flex-end;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-normal);
}

.modal-overlay.open { opacity: 1; pointer-events: all; }

@media (min-width: 768px) {
  .modal-overlay { align-items: center; }
}

.modal {
  background: var(--bg-surface);
  border-radius: var(--radius-xl) var(--radius-xl) 0 0;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  transform: translateY(100%);
  transition: transform var(--transition-slow);
}

.modal-overlay.open .modal { transform: translateY(0); }

@media (min-width: 768px) {
  .modal {
    max-width: 560px;
    border-radius: var(--radius-xl);
    transform: scale(0.95);
  }
  .modal-overlay.open .modal { transform: scale(1); }
}

.modal-header { padding: var(--space-lg); border-bottom: 1px solid var(--border-color); display: flex; align-items: center; justify-content: space-between; }
.modal-body { padding: var(--space-lg); }
.modal-footer { padding: var(--space-md) var(--space-lg); border-top: 1px solid var(--border-color); display: flex; gap: var(--space-sm); justify-content: flex-end; }

/* ── AI Chat Bubble ── */
.chat-container { display: flex; flex-direction: column; gap: var(--space-md); max-height: 60vh; overflow-y: auto; padding: var(--space-md); }

.chat-bubble {
  max-width: 85%;
  padding: var(--space-md);
  border-radius: var(--radius-lg);
  font-size: 14px;
  line-height: 1.6;
}

.chat-bubble.user { align-self: flex-end; background: var(--color-primary); color: #FFF; border-bottom-right-radius: var(--radius-sm); }
.chat-bubble.ai { align-self: flex-start; background: var(--bg-surface-hover); color: var(--text-primary); border-bottom-left-radius: var(--radius-sm); }

.chat-input-bar {
  display: flex;
  gap: var(--space-sm);
  padding: var(--space-md);
  background: var(--bg-surface);
  border-top: 1px solid var(--border-color);
}

.chat-input-bar input { flex: 1; }

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

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.animate-in { animation: fadeInUp 0.4s ease-out; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* ── Loading Spinner ── */
.spinner {
  width: 24px;
  height: 24px;
  border: 3px solid var(--border-color);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

/* ── Empty State ── */
.empty-state {
  text-align: center;
  padding: var(--space-2xl);
  color: var(--text-muted);
}

.empty-state svg { width: 64px; height: 64px; margin: 0 auto var(--space-md); opacity: 0.3; }

/* ── Utilities ── */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.gap-lg { gap: var(--space-lg); }
.text-center { text-align: center; }
.text-sm { font-size: 13px; }
.text-muted { color: var(--text-muted); }
.font-bold { font-weight: 700; }
.mt-md { margin-top: var(--space-md); }
.mb-md { margin-bottom: var(--space-md); }
.hidden { display: none; }

@media (min-width: 768px) { .md\:flex { display: flex; } .md\:hidden { display: none; } }
@media (min-width: 1024px) { .lg\:flex { display: flex; } .lg\:hidden { display: none; } }