:root {
  --primary-color: #4f46e5;
  --primary-dark: #4338ca;
  --secondary-color: #10b981;
  --danger-color: #ef4444;
  --warning-color: #f59e0b;
  --bg-color: #f9fafb;
  --card-bg: #ffffff;
  --text-primary: #111827;
  --text-secondary: #6b7280;
  --border-color: #e5e7eb;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Navigation */
.navbar {
  background-color: var(--card-bg);
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 2rem;
  max-width: 1400px;
  margin: 0 auto;
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-menu {
  display: flex;
  gap: 2rem;
  align-items: center;
  list-style: none;
}

.nav-menu a {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--primary-color);
}

.user-info {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.user-avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 600;
}

/* Auth Pages */
.auth-container {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  padding: 2rem;
}

.auth-card {
  background: var(--card-bg);
  padding: 3rem;
  border-radius: 12px;
  box-shadow: var(--shadow-lg);
  width: 100%;
  max-width: 450px;
}

.auth-header {
  text-align: center;
  margin-bottom: 2rem;
}

.auth-header h1 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.auth-header p {
  color: var(--text-secondary);
}

/* Forms */
.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  color: var(--text-primary);
}

.form-control {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  font-size: 1rem;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.form-control:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.form-error {
  color: var(--danger-color);
  font-size: 0.875rem;
  margin-top: 0.5rem;
  display: none;
}

.form-error.show {
  display: block;
}

/* Buttons */
.btn {
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

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

.btn-primary:hover {
  background-color: var(--primary-dark);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background-color: var(--secondary-color);
  color: white;
}

.btn-danger {
  background-color: var(--danger-color);
  color: white;
}

.btn-outline {
  background-color: transparent;
  border: 2px solid var(--primary-color);
  color: var(--primary-color);
}

.btn-block {
  width: 100%;
}

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

/* Dashboard */
.dashboard {
  padding: 2rem 0;
}

.page-header {
  margin-bottom: 2rem;
}

.page-header h1 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

.page-header p {
  color: var(--text-secondary);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.stat-card {
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 12px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-color);
}

.stat-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 1rem;
}

.stat-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.stat-icon.primary {
  background-color: rgba(79, 70, 229, 0.1);
  color: var(--primary-color);
}

.stat-icon.success {
  background-color: rgba(16, 185, 129, 0.1);
  color: var(--secondary-color);
}

.stat-icon.warning {
  background-color: rgba(245, 158, 11, 0.1);
  color: var(--warning-color);
}

.stat-value {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
}

.stat-label {
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.stat-change {
  font-size: 0.875rem;
  margin-top: 0.5rem;
}

.stat-change.positive {
  color: var(--secondary-color);
}

.stat-change.negative {
  color: var(--danger-color);
}

/* Cards */
.card {
  background: var(--card-bg);
  border-radius: 12px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-color);
  margin-bottom: 1.5rem;
}

.card-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.card-title {
  font-size: 1.25rem;
  font-weight: 600;
}

.card-body {
  padding: 1.5rem;
}

/* Table */
.table-container {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
}

thead {
  background-color: var(--bg-color);
}

th {
  padding: 1rem;
  text-align: left;
  font-weight: 600;
  color: var(--text-secondary);
  font-size: 0.875rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

td {
  padding: 1rem;
  border-top: 1px solid var(--border-color);
}

tr:hover {
  background-color: var(--bg-color);
}

/* Badges */
.badge {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 600;
}

.badge-success {
  background-color: rgba(16, 185, 129, 0.1);
  color: var(--secondary-color);
}

.badge-warning {
  background-color: rgba(245, 158, 11, 0.1);
  color: var(--warning-color);
}

.badge-danger {
  background-color: rgba(239, 68, 68, 0.1);
  color: var(--danger-color);
}

.badge-info {
  background-color: rgba(79, 70, 229, 0.1);
  color: var(--primary-color);
}

/* Loading */
.loading {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 3px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: white;
  animation: spin 0.6s linear infinite;
}

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

/* Alert */
.alert {
  padding: 1rem 1.5rem;
  border-radius: 6px;
  margin-bottom: 1rem;
  display: none;
}

.alert.show {
  display: block;
}

.alert-success {
  background-color: rgba(16, 185, 129, 0.1);
  color: var(--secondary-color);
  border: 1px solid var(--secondary-color);
}

.alert-error {
  background-color: rgba(239, 68, 68, 0.1);
  color: var(--danger-color);
  border: 1px solid var(--danger-color);
}

.alert-info {
  background-color: rgba(79, 70, 229, 0.1);
  color: var(--primary-color);
  border: 1px solid var(--primary-color);
}

/* Modal */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 1000;
  align-items: center;
  justify-content: center;
}

.modal.show {
  display: flex;
}

.modal-content {
  background: var(--card-bg);
  border-radius: 12px;
  max-width: 600px;
  width: 90%;
  max-height: 90vh;
  overflow-y: auto;
}

.modal-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.modal-title {
  font-size: 1.5rem;
  font-weight: 600;
}

.modal-close {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-secondary);
  padding: 0;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 6px;
  transition: background-color 0.2s;
}

.modal-close:hover {
  background-color: var(--bg-color);
}

.modal-body {
  padding: 1.5rem;
}

.modal-footer {
  padding: 1.5rem;
  border-top: 1px solid var(--border-color);
  display: flex;
  gap: 1rem;
  justify-content: flex-end;
}

/* Utilities */
.text-center {
  text-align: center;
}

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.flex {
  display: flex;
}

.flex-between {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }
.gap-3 { gap: 1.5rem; }

.hidden {
  display: none !important;
}

/* Settings Dropdown */
.settings-menu {
  position: absolute;
  right: 0;
  top: 100%;
  margin-top: 0.5rem;
  background: white;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  box-shadow: var(--shadow-lg);
  min-width: 200px;
  z-index: 1000;
}

.settings-menu a {
  display: block;
  padding: 0.75rem 1rem;
  color: var(--text-primary);
  text-decoration: none;
  border-bottom: 1px solid var(--border-color);
  transition: background-color 0.2s;
}

.settings-menu a:last-child {
  border-bottom: none;
}

.settings-menu a:hover {
  background-color: var(--bg-color);
}

.settings-menu a.danger {
  color: var(--danger-color);
}

/* ============================================
   MOBILE RESPONSIVE DESIGN
   ============================================ */

/* Tablet and below (1024px) */
@media (max-width: 1024px) {
  .container {
    padding: 0 15px;
  }

  .nav-content {
    padding: 1rem 1.5rem;
  }

  .nav-menu {
    gap: 1.5rem;
    font-size: 0.9rem;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }

  .card-header {
    flex-direction: column;
    align-items: flex-start !important;
    gap: 1rem;
  }

  .card-header .btn {
    width: 100%;
  }
}

/* Mobile (768px and below) */
@media (max-width: 768px) {
  body {
    font-size: 14px;
  }

  .container {
    padding: 0 12px;
  }

  /* Navigation - Hide menu items, show mobile menu */
  .nav-content {
    padding: 0.75rem 1rem;
    flex-wrap: wrap;
  }

  .logo {
    font-size: 1.25rem;
  }

  .nav-menu {
    display: none; /* Hide desktop menu on mobile */
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--card-bg);
    flex-direction: column;
    padding: 1rem;
    border-top: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
    gap: 0;
  }

  .nav-menu.mobile-open {
    display: flex;
  }

  .nav-menu li {
    width: 100%;
    border-bottom: 1px solid var(--border-color);
  }

  .nav-menu li:last-child {
    border-bottom: none;
  }

  .nav-menu a {
    display: block;
    padding: 1rem;
    width: 100%;
  }

  .user-info {
    gap: 0.5rem;
  }

  .user-avatar {
    width: 32px;
    height: 32px;
    font-size: 0.9rem;
  }

  /* Dashboard */
  .dashboard {
    padding: 1rem 0;
  }

  .page-header {
    margin-bottom: 1.5rem;
  }

  .page-header h1 {
    font-size: 1.5rem;
  }

  .page-header p {
    font-size: 0.9rem;
  }

  /* Stats Grid */
  .stats-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  .stat-card {
    padding: 1.25rem;
  }

  .stat-value {
    font-size: 1.75rem;
  }

  .stat-icon {
    width: 40px;
    height: 40px;
    font-size: 1.25rem;
  }

  /* Cards */
  .card {
    margin-bottom: 1rem;
  }

  .card-header {
    padding: 1rem;
  }

  .card-title {
    font-size: 1.1rem;
  }

  .card-body {
    padding: 1rem;
  }

  /* Tables */
  .table-container {
    font-size: 0.85rem;
    -webkit-overflow-scrolling: touch;
  }

  th, td {
    padding: 0.75rem 0.5rem;
    font-size: 0.85rem;
  }

  th {
    font-size: 0.75rem;
  }

  /* Buttons */
  .btn {
    padding: 0.65rem 1.25rem;
    font-size: 0.9rem;
  }

  /* Forms */
  .form-control {
    padding: 0.65rem 0.85rem;
    font-size: 0.95rem;
  }

  /* Auth Pages */
  .auth-container {
    padding: 1rem;
  }

  .auth-card {
    padding: 1.5rem;
  }

  .auth-header h1 {
    font-size: 1.5rem;
  }

  /* Modal */
  .modal-content {
    width: 95%;
    margin: 1rem;
  }

  .modal-header,
  .modal-body,
  .modal-footer {
    padding: 1rem;
  }

  .modal-title {
    font-size: 1.25rem;
  }

  .modal-footer {
    flex-direction: column;
  }

  .modal-footer .btn {
    width: 100%;
  }

  /* Settings Menu */
  .settings-menu {
    min-width: 180px;
    right: -10px;
  }

  .settings-menu a {
    padding: 0.65rem 0.85rem;
    font-size: 0.9rem;
  }

  /* Badges */
  .badge {
    padding: 0.2rem 0.6rem;
    font-size: 0.7rem;
  }
}

/* Small Mobile (480px and below) */
@media (max-width: 480px) {
  .container {
    padding: 0 10px;
  }

  .nav-content {
    padding: 0.65rem 0.85rem;
  }

  .logo {
    font-size: 1.1rem;
  }

  .user-avatar {
    width: 28px;
    height: 28px;
    font-size: 0.8rem;
  }

  .page-header h1 {
    font-size: 1.25rem;
  }

  .page-header p {
    font-size: 0.85rem;
  }

  .stat-card {
    padding: 1rem;
  }

  .stat-value {
    font-size: 1.5rem;
  }

  .stat-label {
    font-size: 0.8rem;
  }

  .stat-icon {
    width: 36px;
    height: 36px;
    font-size: 1.1rem;
  }

  .card-header {
    padding: 0.85rem;
  }

  .card-title {
    font-size: 1rem;
  }

  .card-body {
    padding: 0.85rem;
  }

  .btn {
    padding: 0.6rem 1rem;
    font-size: 0.85rem;
  }

  .auth-card {
    padding: 1.25rem;
  }

  .auth-header h1 {
    font-size: 1.35rem;
  }

  table {
    font-size: 0.8rem;
  }

  th, td {
    padding: 0.5rem 0.35rem;
  }

  .modal-content {
    width: 98%;
    margin: 0.5rem;
  }
}

/* Landscape Mobile Optimization */
@media (max-width: 768px) and (orientation: landscape) {
  .auth-container {
    padding: 1rem;
  }

  .modal-content {
    max-height: 85vh;
  }
}

/* Print Styles */
@media print {
  .navbar,
  .btn,
  .settings-menu {
    display: none !important;
  }

  .card {
    break-inside: avoid;
    box-shadow: none;
    border: 1px solid #ddd;
  }
}