/* Dark Mode CSS - Central theme management */
:root {
    /* Light mode colors (default) */
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --bg-card: #ffffff;
    --bg-sidebar: #ffffff;
    --bg-header: #ffffff;
    --bg-modal: #ffffff;
    --bg-input: #ffffff;
    --bg-button: #3b82f6;
    --bg-button-hover: #2563eb;
    --bg-gradient-start: #667eea;
    --bg-gradient-end: #764ba2;
    --bg-gradient-hero: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --bg-gradient-card: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --text-inverse: #ffffff;
    --text-link: #2563eb;
    --text-link-hover: #1d4ed8;
    
    --border-primary: #e2e8f0;
    --border-secondary: #cbd5e1;
    --border-focus: #3b82f6;
    --border-input: #d1d5db;
    
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-card: 0 10px 20px rgba(0, 0, 0, 0.05);
    --shadow-button: 0 4px 12px rgba(59, 130, 246, 0.3);
    
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --info: #3b82f6;
    
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    
    --transition: all 0.3s ease;
    --transition-fast: all 0.2s ease;
  }
  
  /* Dark mode colors */
  [data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --bg-card: #1e293b;
    --bg-sidebar: #1e293b;
    --bg-header: #1e293b;
    --bg-modal: #1e293b;
    --bg-input: #334155;
    --bg-button: #3b82f6;
    --bg-button-hover: #2563eb;
    --bg-gradient-start: #1e40af;
    --bg-gradient-end: #1e3a8a;
    --bg-gradient-hero: linear-gradient(135deg, #1e40af 0%, #1e3a8a 100%);
    --bg-gradient-card: linear-gradient(135deg, #1e293b 0%, #334155 100%);
    
    /* Improved text contrast for dark mode */
    --text-primary: #ffffff;
    --text-secondary: #e2e8f0;
    --text-muted: #cbd5e1;
    --text-inverse: #0f172a;
    --text-link: #93c5fd;
    --text-link-hover: #60a5fa;
    
    --border-primary: #334155;
    --border-secondary: #475569;
    --border-focus: #60a5fa;
    --border-input: #475569;
    
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -2px rgba(0, 0, 0, 0.2);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.3), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
    --shadow-card: 0 10px 20px rgba(0, 0, 0, 0.2);
    --shadow-button: 0 4px 12px rgba(96, 165, 250, 0.3);
    
    --success: #34d399;
    --warning: #fbbf24;
    --error: #f87171;
    --info: #60a5fa;
  }
  
  /* System preference detection */
  @media (prefers-color-scheme: dark) {
    :root:not([data-theme]) {
      --bg-primary: #0f172a;
      --bg-secondary: #1e293b;
      --bg-tertiary: #334155;
      --bg-card: #1e293b;
      --bg-sidebar: #1e293b;
      --bg-header: #1e293b;
      --bg-modal: #1e293b;
      --bg-input: #334155;
      --bg-button: #3b82f6;
      --bg-button-hover: #2563eb;
      --bg-gradient-start: #1e40af;
      --bg-gradient-end: #1e3a8a;
      --bg-gradient-hero: linear-gradient(135deg, #1e40af 0%, #1e3a8a 100%);
      --bg-gradient-card: linear-gradient(135deg, #1e293b 0%, #334155 100%);
      
      --text-primary: #f1f5f9;
      --text-secondary: #cbd5e1;
      --text-muted: #94a3b8;
      --text-inverse: #0f172a;
      --text-link: #60a5fa;
      --text-link-hover: #3b82f6;
      
      --border-primary: #334155;
      --border-secondary: #475569;
      --border-focus: #60a5fa;
      --border-input: #475569;
      
      --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
      --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
      --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -2px rgba(0, 0, 0, 0.2);
      --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.3), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
      --shadow-card: 0 10px 20px rgba(0, 0, 0, 0.2);
      --shadow-button: 0 4px 12px rgba(96, 165, 250, 0.3);
      
      --success: #34d399;
      --warning: #fbbf24;
      --error: #f87171;
      --info: #60a5fa;
    }
  }
  
  /* Dark mode toggle button styles */
  .dark-mode-toggle {
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border: 2px solid var(--border-primary);
    border-radius: 50%;
    background: var(--bg-card);
    color: var(--text-primary);
    cursor: pointer;
    transition: var(--transition-fast);
    box-shadow: var(--shadow-sm);
  }
  
  .dark-mode-toggle:hover {
    background: var(--bg-tertiary);
    border-color: var(--border-focus);
    transform: scale(1.05);
    box-shadow: var(--shadow-md);
  }
  
  .dark-mode-toggle:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
  }
  
  .dark-mode-toggle svg {
    width: 20px;
    height: 20px;
    transition: var(--transition-fast);
  }
  
  .dark-mode-toggle .sun-icon {
    display: block;
  }
  
  .dark-mode-toggle .moon-icon {
    display: none;
  }
  
  [data-theme="dark"] .dark-mode-toggle .sun-icon {
    display: none;
  }
  
  [data-theme="dark"] .dark-mode-toggle .moon-icon {
    display: block;
  }
  
  /* Global dark mode styles */
  body {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    transition: var(--transition);
  }
  
  /* Card styles */
  .card, .glass-card, .announcement-card, .feature-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-primary);
    box-shadow: var(--shadow-card);
    color: var(--text-primary);
  }
  
  /* Dashboard stats and numbers */
  [data-theme="dark"] .stat-number,
  [data-theme="dark"] .stat-value,
  [data-theme="dark"] .dashboard-number {
    color: #ffffff;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
  }
  
  /* Improve card content visibility in dark mode */
  [data-theme="dark"] .card-title,
  [data-theme="dark"] .card-header {
    color: #ffffff;
  }
  
  [data-theme="dark"] .card-subtitle,
  [data-theme="dark"] .card-description {
    color: #e2e8f0;
  }
  
  /* Dashboard status indicators */
  [data-theme="dark"] .status-indicator {
    opacity: 0.9;
  }
  
  /* Improve table text visibility in dark mode */
  [data-theme="dark"] table {
    color: #ffffff;
  }
  
  [data-theme="dark"] td,
  [data-theme="dark"] th {
    color: #e2e8f0;
  }
  
  /* Statistics and metrics in dark mode */
  [data-theme="dark"] .metric-value {
    color: #ffffff;
    font-weight: 600;
  }
  
  [data-theme="dark"] .metric-label {
    color: #cbd5e1;
  }
  
  /* Form styles */
  .form-input, input, textarea, select {
    background-color: var(--bg-input);
    border: 1px solid var(--border-input);
    color: var(--text-primary);
    transition: var(--transition-fast);
  }
  
  .form-input:focus, input:focus, textarea:focus, select:focus {
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
    outline: none;
  }
  
  .form-input::placeholder, input::placeholder, textarea::placeholder {
    color: var(--text-muted);
  }
  
  /* Button styles */
  .btn, .login-button, .btn-primary {
    background-color: var(--bg-button);
    color: var(--text-inverse);
    border: 1px solid var(--bg-button);
    transition: var(--transition-fast);
  }
  
  .btn:hover, .login-button:hover, .btn-primary:hover {
    background-color: var(--bg-button-hover);
    border-color: var(--bg-button-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-button);
  }
  
  /* Modal styles */
  .modal-content {
    background-color: var(--bg-modal);
    border: 1px solid var(--border-primary);
    color: var(--text-primary);
  }
  
  .modal-header {
    border-bottom: 1px solid var(--border-primary);
  }
  
  .modal-footer {
    border-top: 1px solid var(--border-primary);
  }
  
  /* Sidebar styles */
  .sidebar {
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-primary);
    color: var(--text-primary);
  }
  
  /* Header styles */
  .header, .top-navbar {
    background-color: var(--bg-header);
    border-bottom: 1px solid var(--border-primary);
    color: var(--text-primary);
  }
  
  /* Link styles */
  a {
    color: var(--text-link);
    transition: var(--transition-fast);
  }
  
  a:hover {
    color: var(--text-link-hover);
  }
  
  /* Alert styles */
  .alert {
    border: 1px solid var(--border-primary);
    background-color: var(--bg-card);
    color: var(--text-primary);
  }
  
  .alert-success {
    background-color: rgba(16, 185, 129, 0.1);
    border-color: var(--success);
    color: var(--success);
  }
  
  .alert-warning {
    background-color: rgba(245, 158, 11, 0.1);
    border-color: var(--warning);
    color: var(--warning);
  }
  
  .alert-danger {
    background-color: rgba(239, 68, 68, 0.1);
    border-color: var(--error);
    color: var(--error);
  }
  
  .alert-info {
    background-color: rgba(59, 130, 246, 0.1);
    border-color: var(--info);
    color: var(--info);
  }
  
  /* Table styles */
  table {
    background-color: var(--bg-card);
    color: var(--text-primary);
  }
  
  th, td {
    border-color: var(--border-primary);
  }
  
  /* Code styles */
  code, pre {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-primary);
  }
  
  /* Scrollbar styles */
  ::-webkit-scrollbar {
    width: 8px;
  }
  
  ::-webkit-scrollbar-track {
    background: var(--bg-secondary);
  }
  
  ::-webkit-scrollbar-thumb {
    background: var(--border-secondary);
    border-radius: 4px;
  }
  
  ::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
  }
  
  /* Selection styles */
  ::selection {
    background-color: var(--bg-button);
    color: var(--text-inverse);
  }
  
  /* Focus styles */
  *:focus {
    outline: 2px solid var(--border-focus);
    outline-offset: 2px;
  }
  
  /* Animation for theme transitions */
  * {
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease, box-shadow 0.3s ease;
  }