/* ===================================================================
   Plateforme d'exercices - Styles globaux
   =================================================================== */

:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #dbeafe;
  --success: #16a34a;
  --success-light: #dcfce7;
  --warning: #f59e0b;
  --warning-light: #fef3c7;
  --error: #dc2626;
  --error-light: #fee2e2;
  --border: #e2e8f0;
  --bg: #f8fafc;
  --card: #ffffff;
  --text: #1e293b;
  --muted: #64748b;
  --accent: #f1f5f9;
  --sidebar-bg: #1e293b;
  --sidebar-text: #cbd5e1;
  --sidebar-active: #2563eb;
}

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

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

/* ---- Login Page ---- */
.login-container {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 20px;
  background: linear-gradient(135deg, #1e293b 0%, #334155 100%);
}

.login-card {
  background: var(--card);
  border-radius: 16px;
  padding: 40px;
  width: 100%;
  max-width: 420px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.login-card h1 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--text);
}

.login-card .subtitle {
  color: var(--muted);
  font-size: 14px;
  margin-bottom: 32px;
}

.login-card .logo {
  font-size: 40px;
  margin-bottom: 16px;
  display: block;
}

/* ---- Forms ---- */
.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 6px;
}

.form-input {
  width: 100%;
  padding: 10px 14px;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  font-size: 14px;
  color: var(--text);
  background: var(--card);
  transition: border-color 0.2s, box-shadow 0.2s;
  outline: none;
}

.form-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.form-input::placeholder {
  color: #94a3b8;
}

select.form-input {
  cursor: pointer;
}

textarea.form-input {
  resize: vertical;
  min-height: 80px;
}

/* ---- Buttons ---- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  background: var(--card);
  color: var(--text);
  transition: all 0.15s ease;
  text-decoration: none;
}

.btn:hover {
  background: var(--accent);
  transform: translateY(-1px);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.btn:active {
  transform: translateY(0);
}

.btn-primary {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

.btn-primary:hover {
  background: var(--primary-dark);
}

.btn-success {
  background: var(--success);
  color: #fff;
  border-color: var(--success);
}

.btn-success:hover {
  background: #15803d;
}

.btn-danger {
  background: var(--error);
  color: #fff;
  border-color: var(--error);
}

.btn-danger:hover {
  background: #b91c1c;
}

.btn-sm {
  padding: 6px 14px;
  font-size: 13px;
  border-radius: 8px;
}

.btn-block {
  width: 100%;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

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

/* Sidebar */
.sidebar {
  width: 260px;
  background: var(--sidebar-bg);
  color: var(--sidebar-text);
  padding: 24px 0;
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 100;
  transition: transform 0.3s;
}

.sidebar-header {
  padding: 0 20px 24px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  margin-bottom: 16px;
}

.sidebar-header h2 {
  font-size: 18px;
  font-weight: 700;
  color: #fff;
  margin-bottom: 4px;
}

.sidebar-header .user-info {
  font-size: 12px;
  color: var(--sidebar-text);
}

.sidebar-header .role-badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  margin-top: 8px;
}

.role-badge.admin { background: #7c3aed; color: #fff; }
.role-badge.professor { background: #0891b2; color: #fff; }
.role-badge.student { background: #059669; color: #fff; }

.sidebar-nav {
  flex: 1;
  padding: 0 12px;
}

.sidebar-nav a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  color: var(--sidebar-text);
  text-decoration: none;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  transition: all 0.15s;
  margin-bottom: 4px;
}

.sidebar-nav a:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
}

.sidebar-nav a.active {
  background: var(--sidebar-active);
  color: #fff;
}

.sidebar-nav .nav-icon {
  font-size: 18px;
  width: 24px;
  text-align: center;
}

.sidebar-footer {
  padding: 16px 12px 0;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  margin-top: auto;
}

/* Main content */
.main-content {
  flex: 1;
  margin-left: 260px;
  padding: 32px;
  max-width: 1200px;
}

.page-header {
  margin-bottom: 28px;
}

.page-header h1 {
  font-size: 24px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 4px;
}

.page-header p {
  color: var(--muted);
  font-size: 14px;
}

/* ---- Cards ---- */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
  margin-bottom: 16px;
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.card-header h3 {
  font-size: 16px;
  font-weight: 600;
}

/* ---- Grid ---- */
.grid {
  display: grid;
  gap: 16px;
}

.grid-2 { grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); }

/* ---- Stats ---- */
.stat-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  text-align: center;
}

.stat-card .stat-icon {
  font-size: 32px;
  margin-bottom: 8px;
}

.stat-card .stat-value {
  font-size: 28px;
  font-weight: 700;
  color: var(--text);
}

.stat-card .stat-label {
  font-size: 13px;
  color: var(--muted);
  margin-top: 4px;
}

/* ---- Course Card ---- */
.course-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  transition: all 0.2s;
  cursor: pointer;
}

.course-card:hover {
  border-color: var(--primary);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.1);
  transform: translateY(-2px);
}

.course-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}

.course-card p {
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 16px;
}

.course-card .course-meta {
  display: flex;
  gap: 16px;
  font-size: 12px;
  color: var(--muted);
}

/* ---- Exercise List ---- */
.exercise-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border: 1px solid var(--border);
  border-radius: 10px;
  margin-bottom: 8px;
  background: var(--card);
  transition: all 0.15s;
  cursor: pointer;
}

.exercise-item:hover {
  border-color: var(--primary);
  background: var(--primary-light);
}

.exercise-item .exercise-info h4 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 2px;
}

.exercise-item .exercise-info p {
  font-size: 12px;
  color: var(--muted);
}

.exercise-item .exercise-score {
  font-size: 13px;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: 20px;
}

.score-done { background: var(--success-light); color: var(--success); }
.score-pending { background: var(--accent); color: var(--muted); }

/* ---- Table ---- */
.data-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  font-size: 14px;
}

.data-table th {
  background: var(--accent);
  padding: 10px 14px;
  text-align: left;
  font-size: 12px;
  font-weight: 600;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.3px;
  border-bottom: 2px solid var(--border);
}

.data-table td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
}

.data-table tr:hover td {
  background: var(--accent);
}

/* ---- Exercise Viewer ---- */
.exercise-viewer {
  display: flex;
  flex-direction: column;
  height: calc(100vh - 64px);
}

.exercise-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 20px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
}

.exercise-toolbar h2 {
  font-size: 16px;
  font-weight: 600;
}

.exercise-frame-container {
  flex: 1;
  position: relative;
  overflow: hidden;
}

.exercise-frame-container iframe {
  width: 100%;
  height: 100%;
  border: none;
  background: #fff;
}

/* ---- Modal ---- */
.modal-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 1000;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal-overlay.active {
  display: flex;
}

.modal {
  background: var(--card);
  border-radius: 16px;
  padding: 28px;
  width: 100%;
  max-width: 600px;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.modal h2 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 20px;
}

.modal-actions {
  display: flex;
  gap: 10px;
  justify-content: flex-end;
  margin-top: 24px;
}

/* ---- Alerts ---- */
.alert {
  padding: 12px 16px;
  border-radius: 10px;
  font-size: 14px;
  margin-bottom: 16px;
  display: none;
}

.alert.visible {
  display: block;
}

.alert-error {
  background: var(--error-light);
  color: var(--error);
  border: 1px solid #fca5a5;
}

.alert-success {
  background: var(--success-light);
  color: var(--success);
  border: 1px solid #86efac;
}

.alert-warning {
  background: var(--warning-light);
  color: #92400e;
  border: 1px solid #fcd34d;
}

/* ---- Spinner ---- */
.spinner {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 2.5px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}

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

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.loading-screen {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 200px;
  flex-direction: column;
  gap: 12px;
  color: var(--muted);
}

/* ---- Empty State ---- */
.empty-state {
  text-align: center;
  padding: 48px 20px;
  color: var(--muted);
}

.empty-state .empty-icon {
  font-size: 48px;
  margin-bottom: 12px;
}

.empty-state h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 8px;
}

.empty-state p {
  font-size: 14px;
  max-width: 400px;
  margin: 0 auto;
}

/* ---- Tabs ---- */
.tabs {
  display: flex;
  gap: 4px;
  border-bottom: 2px solid var(--border);
  margin-bottom: 20px;
}

.tab {
  padding: 10px 20px;
  font-size: 14px;
  font-weight: 500;
  color: var(--muted);
  cursor: pointer;
  border: none;
  background: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: all 0.15s;
}

.tab:hover {
  color: var(--text);
}

.tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

/* ---- Responsive ---- */
@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
  }

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

  .main-content {
    margin-left: 0;
    padding: 20px;
  }

  .mobile-menu-btn {
    display: flex !important;
  }

  .grid-2, .grid-3, .grid-4 {
    grid-template-columns: 1fr;
  }

  .modal {
    max-width: 100%;
    margin: 10px;
  }
}

.mobile-menu-btn {
  display: none;
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 200;
  background: var(--sidebar-bg);
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 8px 12px;
  font-size: 20px;
  cursor: pointer;
}

/* ---- Utility ---- */
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-muted { color: var(--muted); }
.text-success { color: var(--success); }
.text-error { color: var(--error); }
.text-sm { font-size: 13px; }
.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.gap-row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.flex-between { display: flex; justify-content: space-between; align-items: center; }
.hidden { display: none !important; }