/**
 * Saint Isidore College Admin Dashboard — Unified Design System
 * Version: 2.0.0
 * Date: October 30, 2025
 * 
 * This stylesheet implements a calm, consistent, SaaS-quality design system
 * for the admin dashboard. All visual patterns are standardized across tabs.
 * 
 * STRUCTURE:
 * 1. Design Tokens (CSS Variables)
 * 2. Global Resets & Base Styles
 * 3. Layout Components (Header, Main)
 * 4. Navigation (Tabs)
 * 5. Filter Bar
 * 6. Tables (Canonical Pattern)
 * 7. Buttons & Form Controls
 * 8. Cards & Containers
 * 9. Loading & Empty States
 * 10. Utility Classes
 * 11. Responsive Breakpoints
 */

/* ============================================================
   1. DESIGN TOKENS — Single Source of Truth
   ============================================================ */

:root {
  /* Spacing Scale (8px base unit) */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-12: 48px;
  --space-16: 64px;

  /* Typography Scale */
  --text-xs: 12px;
  --text-sm: 14px;
  --text-base: 16px;
  --text-lg: 18px;
  --text-xl: 20px;
  --text-2xl: 24px;
  
  --leading-tight: 1.25;
  --leading-snug: 1.375;
  --leading-normal: 1.5;
  --leading-relaxed: 1.625;
  
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;
  
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", Monaco, "Cascadia Code", "Courier New", monospace;

  /* Color Palette */
  --color-primary: #003057;
  --color-primary-hover: #00244a;
  --color-primary-active: #001d3d;
  --color-accent: #660000;
  --color-accent-hover: #800000;
  
  /* Backgrounds */
  --color-bg: #ffffff;
  --color-bg-subtle: #f9fafb;
  --color-bg-muted: #f3f4f6;
  --color-bg-hover: #f9fafb;
  
  /* Borders */
  --color-border: #e5e7eb;
  --color-border-hover: #d1d5db;
  --color-border-focus: #9ca3af;
  
  /* Text */
  --color-text: #111827;
  --color-text-secondary: #6b7280;
  --color-text-tertiary: #9ca3af;
  --color-text-disabled: #d1d5db;
  
  /* Semantic Colors */
  --color-success: #059669;
  --color-success-bg: #d1fae5;
  --color-warning: #d97706;
  --color-warning-bg: #fef3c7;
  --color-danger: #dc2626;
  --color-danger-bg: #fee2e2;
  --color-info: #2563eb;
  --color-info-bg: #dbeafe;
  
  /* Focus States */
  --color-focus: #2563eb;
  --focus-ring: 0 0 0 3px rgba(37, 99, 235, 0.1);
  --focus-ring-danger: 0 0 0 3px rgba(220, 38, 38, 0.1);

  /* Elevation (Shadows) */
  --shadow-none: none;
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 4px 8px rgba(0, 0, 0, 0.08);
  
  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-xl: 12px;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.2s ease;
  --transition-slow: 0.3s ease;
  
  /* Layout Dimensions */
  --header-height: 60px;
  --tabs-height: 48px;
  --filter-bar-height: 68px;
  --table-footer-height: 48px;
  --table-row-height: 40px;
  --table-header-height: 40px;
  
  /* Z-Index Scale */
  --z-base: 1;
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-modal-backdrop: 900;
  --z-modal: 1000;
  --z-toast: 1100;
}

/* ============================================================
   2. GLOBAL RESETS & BASE STYLES
   ============================================================ */

*, *::before, *::after {
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-family);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--color-text);
  background: var(--color-bg-subtle);
}

h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-weight: var(--font-semibold);
  line-height: var(--leading-tight);
}

p {
  margin: 0;
}

button {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
}

input, select, textarea {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
}

/* ============================================================
   3. LAYOUT COMPONENTS
   ============================================================ */

.admin-layout {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Header */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
  padding: 0 var(--space-6);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
}

.header__brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.header__title {
  font-size: var(--text-xl);
  font-weight: var(--font-bold);
  color: var(--color-primary);
  margin: 0;
}

.header__user {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.header__user-name {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
}

/* Main Content Area */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  max-width: 1600px;
  width: 100%;
  margin: 0 auto;
}

/* Header Section Enhancement */
.header-section {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-6) var(--space-6) var(--space-4);
  background: linear-gradient(135deg, var(--color-primary) 0%, #004275 100%);
  color: white;
  border-bottom: 3px solid var(--color-accent);
}

.header-content h1 {
  font-size: var(--text-2xl);
  font-weight: var(--font-bold);
  margin: 0 0 var(--space-2);
  color: white;
}

.header-content p {
  font-size: var(--text-sm);
  margin: 0;
  color: rgba(255, 255, 255, 0.85);
}

.header-controls {
  display: flex;
  gap: var(--space-3);
  align-items: center;
}

/* Signal Tiles */
.signal-tiles {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-4);
  padding: var(--space-4) var(--space-6);
  background: var(--color-bg-subtle);
  border-bottom: 1px solid var(--color-border);
}

.signal-tile {
  background: white;
  border-radius: var(--radius-md);
  padding: var(--space-4);
  box-shadow: var(--shadow-sm);
  transition: all 0.2s ease;
}

.signal-tile:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.signal-icon {
  font-size: var(--text-2xl);
  margin-bottom: var(--space-3);
  display: block;
  opacity: 0.8;
}

.signal-content {
  margin-bottom: var(--space-2);
}

.signal-label {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-2);
  font-weight: var(--font-medium);
}

.signal-value {
  font-size: var(--text-2xl);
  font-weight: var(--font-bold);
  color: var(--color-primary);
  margin-bottom: var(--space-1);
}

.signal-delta {
  font-size: var(--text-xs);
  font-weight: var(--font-medium);
}

.signal-delta.positive {
  color: var(--color-success);
}

.signal-delta.negative {
  color: var(--color-danger);
}

.signal-delta.neutral {
  color: var(--color-text-tertiary);
}

/* ============================================================
   4. NAVIGATION (TABS)
   ============================================================ */

.tabs {
  display: flex;
  gap: var(--space-1);
  padding: 0 var(--space-6);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  overflow-x: auto;
  scrollbar-width: none; /* Firefox */
  -ms-overflow-style: none; /* IE/Edge */
}

.tabs::-webkit-scrollbar {
  display: none; /* Chrome/Safari */
}

.tab {
  position: relative;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  height: var(--tabs-height);
  padding: 0 var(--space-4);
  border: none;
  background: transparent;
  color: var(--color-text-secondary);
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  cursor: pointer;
  transition: color var(--transition-fast);
  white-space: nowrap;
  flex-shrink: 0;
}

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

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

.tab.active::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-primary);
}

.tab:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: -2px;
  border-radius: var(--radius-sm);
  z-index: 1;
}

.tab__icon {
  font-size: 16px;
  line-height: 1;
}

/* .tab__label: Visible by default, hidden on mobile if needed */

.tab__badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 20px;
  height: 20px;
  padding: 0 6px;
  background: var(--color-bg-muted);
  color: var(--color-text-secondary);
  font-size: var(--text-xs);
  font-weight: var(--font-semibold);
  border-radius: var(--radius-full);
  line-height: 1;
}

.tab.active .tab__badge {
  background: var(--color-primary);
  color: white;
}

/* Tab Panels */
.tab-panel {
  display: none;
  flex: 1;
  flex-direction: column;
}

.tab-panel.active {
  display: flex;
  animation: fadeInPanel var(--transition-base);
}

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

/* ============================================================
   5. FILTER BAR — Consistent Across All Tabs
   ============================================================ */

.filter-bar {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-4) var(--space-6);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  flex-wrap: wrap;
}

.filter-bar__search {
  flex: 1;
  min-width: 240px;
}

.search-input {
  width: 100%;
  height: 36px;
  padding: 0 var(--space-3);
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  color: var(--color-text);
  font-size: var(--text-sm);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.search-input::placeholder {
  color: var(--color-text-tertiary);
}

.search-input:hover {
  border-color: var(--color-border-hover);
}

.search-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: var(--focus-ring);
}

.filter-select {
  height: 36px;
  padding: 0 32px 0 var(--space-3);
  border: 1px solid var(--color-border);
  background: var(--color-bg) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236b7280' d='M6 9L1 4h10z'/%3E%3C/svg%3E") no-repeat right 12px center;
  color: var(--color-text);
  font-size: var(--text-sm);
  border-radius: var(--radius-md);
  appearance: none;
  cursor: pointer;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.filter-select:hover {
  border-color: var(--color-border-hover);
}

.filter-select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: var(--focus-ring);
}

.filter-bar__actions {
  display: flex;
  gap: var(--space-2);
  margin-left: auto;
}

/* Quick Filter Pills (Optional Enhancement) */
.quick-filters {
  display: flex;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  background: var(--color-bg-subtle);
  border-bottom: 1px solid var(--color-border);
}

.quick-filter {
  height: 28px;
  padding: 0 var(--space-3);
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  color: var(--color-text-secondary);
  font-size: var(--text-xs);
  font-weight: var(--font-medium);
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.quick-filter:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.quick-filter.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: white;
}

/* ============================================================
   6. TABLES — Canonical Pattern (Based on Infringements)
   ============================================================ */

.table-wrapper {
  flex: 1;
  display: flex;
  flex-direction: column;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin: var(--space-4) var(--space-6);
}

.table-scroll {
  flex: 1;
  overflow-x: auto;
  overflow-y: auto;
}

/* Scrollbar Styling */
.table-scroll::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

.table-scroll::-webkit-scrollbar-track {
  background: var(--color-bg-subtle);
}

.table-scroll::-webkit-scrollbar-thumb {
  background: var(--color-border-hover);
  border-radius: var(--radius-sm);
}

.table-scroll::-webkit-scrollbar-thumb:hover {
  background: var(--color-border-focus);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
  background: var(--color-bg);
}

/* Table Header */
.data-table thead {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  background: var(--color-bg-subtle);
}

.data-table th {
  height: var(--table-header-height);
  padding: 10px 12px;
  text-align: left;
  font-weight: var(--font-semibold);
  font-size: var(--text-xs);
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.025em;
  border-bottom: 1px solid var(--color-border);
  white-space: nowrap;
}

/* Table Body */
.data-table tbody tr {
  border-bottom: 1px solid var(--color-border);
  transition: background-color var(--transition-fast);
}

.data-table tbody tr:hover {
  background: var(--color-bg-hover);
}

.data-table tbody tr.selected {
  background: var(--color-info-bg);
}

.data-table tbody tr:last-child {
  border-bottom: none;
}

.data-table td {
  height: var(--table-row-height);
  padding: 10px 12px;
  color: var(--color-text);
  vertical-align: middle;
}

/* Cell Type Modifiers */
.cell--checkbox {
  width: 40px;
  text-align: center;
  padding: 0;
}

.cell--checkbox input[type="checkbox"] {
  width: 16px;
  height: 16px;
  cursor: pointer;
  accent-color: var(--color-primary);
}

.cell--sortable {
  padding: 0;
}

.sort-btn {
  width: 100%;
  height: 100%;
  padding: 10px 12px;
  border: none;
  background: transparent;
  text-align: left;
  font-size: var(--text-xs);
  font-weight: var(--font-semibold);
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.025em;
  cursor: pointer;
  transition: background-color var(--transition-fast);
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

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

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

.sort-btn::after {
  content: '';
  width: 0;
  height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.sort-btn.sort-asc::after {
  border-bottom: 4px solid var(--color-text-secondary);
  opacity: 1;
}

.sort-btn.sort-desc::after {
  border-top: 4px solid var(--color-text-secondary);
  opacity: 1;
}

.cell--meta {
  color: var(--color-text-tertiary);
  font-size: var(--text-xs);
}

.cell--actions {
  width: 100px;
  text-align: right;
}

.cell--number {
  text-align: right;
  font-variant-numeric: tabular-nums;
}

.cell--badge {
  font-size: var(--text-xs);
}

/* Row Expander */
.row-expander {
  width: 24px;
  height: 24px;
  padding: 0;
  border: none;
  background: transparent;
  color: var(--color-text-tertiary);
  cursor: pointer;
  transition: color var(--transition-fast), transform var(--transition-fast);
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

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

.row-expander[aria-expanded="true"] {
  transform: rotate(90deg);
}

/* Empty State */
.table-empty {
  padding: var(--space-12) var(--space-6);
  text-align: center;
  color: var(--color-text-tertiary);
}

.table-empty__icon {
  font-size: 48px;
  opacity: 0.3;
  margin-bottom: var(--space-3);
}

.table-empty__title {
  font-size: var(--text-base);
  font-weight: var(--font-medium);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-1);
}

.table-empty__desc {
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
}

/* Loading State */
.table-loading {
  padding: var(--space-12) var(--space-6);
  text-align: center;
}

.spinner {
  display: inline-block;
  width: 32px;
  height: 32px;
  border: 3px solid var(--color-bg-muted);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* Skeleton Loading Rows */
.skeleton-row td {
  padding: 10px 12px;
}

.skeleton-cell {
  height: 16px;
  background: linear-gradient(
    90deg,
    var(--color-bg-muted) 0%,
    var(--color-bg-subtle) 50%,
    var(--color-bg-muted) 100%
  );
  background-size: 200% 100%;
  border-radius: var(--radius-sm);
  animation: skeleton-shimmer 1.5s ease-in-out infinite;
}

@keyframes skeleton-shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* Table Footer (Pagination & Status) */
.table-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--table-footer-height);
  padding: 0 var(--space-4);
  background: var(--color-bg-subtle);
  border-top: 1px solid var(--color-border);
  font-size: var(--text-sm);
  gap: var(--space-4);
}

.table-footer__info {
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.table-footer__info strong {
  color: var(--color-text);
  font-weight: var(--font-semibold);
}

.table-footer__controls {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.pagination-btn {
  width: 32px;
  height: 32px;
  padding: 0;
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  color: var(--color-text-secondary);
  font-size: var(--text-sm);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: center;
}

.pagination-btn:hover:not(:disabled) {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

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

.pagination-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.pagination-pages {
  color: var(--color-text-secondary);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-sm);
}

.pagination-size {
  height: 32px;
  padding: 0 28px 0 var(--space-2);
  border: 1px solid var(--color-border);
  background: var(--color-bg) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236b7280' d='M6 9L1 4h10z'/%3E%3C/svg%3E") no-repeat right 8px center;
  color: var(--color-text);
  font-size: var(--text-sm);
  border-radius: var(--radius-sm);
  appearance: none;
  cursor: pointer;
  transition: border-color var(--transition-fast);
}

.pagination-size:hover {
  border-color: var(--color-border-hover);
}

.pagination-size:focus {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

/* ============================================================
   7. BUTTONS & FORM CONTROLS
   ============================================================ */

/* Base Button */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  height: 36px;
  padding: 0 var(--space-4);
  border: none;
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

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

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Primary Button */
.btn--primary {
  background: var(--color-primary);
  color: white;
}

.btn--primary:hover:not(:disabled) {
  background: var(--color-primary-hover);
}

.btn--primary:active:not(:disabled) {
  background: var(--color-primary-active);
}

/* Secondary Button */
.btn--secondary {
  background: var(--color-bg);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn--secondary:hover:not(:disabled) {
  background: var(--color-bg-subtle);
  border-color: var(--color-border-hover);
}

/* Danger Button */
.btn--danger {
  background: var(--color-danger);
  color: white;
}

.btn--danger:hover:not(:disabled) {
  background: #b91c1c;
}

.btn--danger:focus-visible {
  outline-color: var(--color-danger);
  box-shadow: var(--focus-ring-danger);
}

/* Ghost Button */
.btn--ghost {
  background: transparent;
  color: var(--color-text-secondary);
}

.btn--ghost:hover:not(:disabled) {
  background: var(--color-bg-subtle);
  color: var(--color-text);
}

/* Small Button */
.btn--sm {
  height: 28px;
  padding: 0 var(--space-3);
  font-size: var(--text-xs);
}

/* Icon-Only Button */
.btn--icon {
  width: 36px;
  padding: 0;
}

.btn--icon.btn--sm {
  width: 28px;
}

/* Form Controls */
.form-group {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.form-label {
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--color-text);
}

.form-input,
.form-textarea {
  width: 100%;
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  color: var(--color-text);
  font-size: var(--text-sm);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-input:hover,
.form-textarea:hover {
  border-color: var(--color-border-hover);
}

.form-input:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: var(--focus-ring);
}

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

/* ============================================================
   8. CARDS & CONTAINERS
   ============================================================ */

.card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.card__header {
  padding: var(--space-4);
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg-subtle);
}

.card__title {
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  color: var(--color-text);
}

.card__body {
  padding: var(--space-4);
}

.card__footer {
  padding: var(--space-4);
  border-top: 1px solid var(--color-border);
  background: var(--color-bg-subtle);
}

/* Stats Cards */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-4);
  padding: var(--space-4) var(--space-6);
}

.stat-card {
  padding: var(--space-4);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: box-shadow var(--transition-base);
}

.stat-card:hover {
  box-shadow: var(--shadow-md);
}

.stat-card__value {
  font-size: var(--text-2xl);
  font-weight: var(--font-bold);
  color: var(--color-text);
  line-height: 1;
}

.stat-card__label {
  margin-top: var(--space-2);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.025em;
}

/* Badge */
.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 2px 8px;
  font-size: var(--text-xs);
  font-weight: var(--font-medium);
  border-radius: var(--radius-sm);
  line-height: 1.5;
}

.badge--primary {
  background: var(--color-primary);
  color: white;
}

.badge--success {
  background: var(--color-success-bg);
  color: var(--color-success);
}

.badge--warning {
  background: var(--color-warning-bg);
  color: var(--color-warning);
}

.badge--danger {
  background: var(--color-danger-bg);
  color: var(--color-danger);
}

.badge--info {
  background: var(--color-info-bg);
  color: var(--color-info);
}

.badge--neutral {
  background: var(--color-bg-muted);
  color: var(--color-text-secondary);
}

/* Alert / Notice Boxes */
.alert {
  padding: var(--space-4);
  border-radius: var(--radius-md);
  margin: var(--space-4) var(--space-6);
}

.alert--info {
  background: var(--color-info-bg);
  border-left: 4px solid var(--color-info);
  color: #1e40af;
}

.alert--success {
  background: var(--color-success-bg);
  border-left: 4px solid var(--color-success);
  color: #065f46;
}

.alert--warning {
  background: var(--color-warning-bg);
  border-left: 4px solid var(--color-warning);
  color: #92400e;
}

.alert--danger {
  background: var(--color-danger-bg);
  border-left: 4px solid var(--color-danger);
  color: #991b1b;
}

/* ============================================================
   9. LOADING & EMPTY STATES
   ============================================================ */

.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(255, 255, 255, 0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: var(--z-modal);
}

.loading-content {
  text-align: center;
}

.loading-content .spinner {
  margin-bottom: var(--space-4);
}

.loading-text {
  font-size: var(--text-base);
  color: var(--color-text-secondary);
}

/* ============================================================
   10. UTILITY CLASSES
   ============================================================ */

/* Visibility */
.hidden {
  display: none !important;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* Text Alignment */
.text-left { text-align: left; }
.text-center { text-align: center; }
.text-right { text-align: right; }

/* Text Colors */
.text-primary { color: var(--color-primary); }
.text-secondary { color: var(--color-text-secondary); }
.text-tertiary { color: var(--color-text-tertiary); }
.text-success { color: var(--color-success); }
.text-warning { color: var(--color-warning); }
.text-danger { color: var(--color-danger); }

/* Font Weights */
.font-normal { font-weight: var(--font-normal); }
.font-medium { font-weight: var(--font-medium); }
.font-semibold { font-weight: var(--font-semibold); }
.font-bold { font-weight: var(--font-bold); }

/* Truncate */
.truncate {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* ============================================================
   11. RESPONSIVE BREAKPOINTS
   ============================================================ */

/* Tablet (768px and below) */
@media (max-width: 768px) {
  .header {
    padding: 0 var(--space-4);
  }
  
  .tabs {
    padding: 0 var(--space-4);
  }
  
  .tab__label {
    display: none;
  }
  
  .filter-bar {
    padding: var(--space-3) var(--space-4);
  }
  
  .filter-bar__search {
    flex: 1 1 100%;
  }
  
  .filter-select {
    flex: 1;
  }
  
  .filter-bar__actions {
    flex: 1 1 100%;
    margin-left: 0;
  }
  
  .btn {
    flex: 1;
  }
  
  .table-wrapper {
    margin: var(--space-3) var(--space-4);
    border-radius: var(--radius-md);
  }
  
  .table-footer {
    flex-wrap: wrap;
    height: auto;
    padding: var(--space-2) var(--space-3);
    gap: var(--space-2);
  }
  
  .table-footer__info {
    flex: 1 1 100%;
    font-size: var(--text-xs);
  }
  
  .table-footer__controls {
    order: 2;
  }
  
  .pagination-size {
    order: 1;
  }
  
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-3);
    padding: var(--space-3) var(--space-4);
  }
}

/* Mobile (480px and below) */
@media (max-width: 480px) {
  .header__title {
    font-size: var(--text-lg);
  }
  
  .tab {
    padding: 0 var(--space-3);
  }
  
  .stats-grid {
    grid-template-columns: 1fr;
  }
  
  .filter-bar__actions {
    flex-direction: column;
  }
}

/* ============================================================
   12. DARK MODE SUPPORT (Future Enhancement)
   ============================================================ */

@media (prefers-color-scheme: dark) {
  /* Uncomment when dark mode is implemented
  :root {
    --color-bg: #111827;
    --color-bg-subtle: #1f2937;
    --color-bg-muted: #374151;
    --color-border: #4b5563;
    --color-text: #f9fafb;
    --color-text-secondary: #d1d5db;
    --color-text-tertiary: #9ca3af;
  }
  */
}