:root {
  --primary-color: #003366;
  --secondary-color: #4A90E2;
  --tertiary-color: #7B68EE;
  --success-color: #2e7d32;
  --danger-color: #c62828;
  --warning-color: #b8860b;
  --text-color: #212529;
  --text-muted: #6c757d;
  --border-color: #dee2e6;
  --bg-color: #f8f9fa;

  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-xxl: 3rem;

  --max-width: 1200px;
  --border-radius: 0.375rem;
  --box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  color: var(--text-color);
  background: var(--bg-color);
  line-height: 1.5;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg) var(--spacing-xxl);
}

header {
  background: white;
  padding: var(--spacing-md) 0;
  margin: 0 0 var(--spacing-xl) 0;
  border-bottom: 1px solid var(--border-color);
}

header h1 {
  color: var(--primary-color);
  font-size: 1.75rem;
}

header p {
  color: var(--text-muted);
  margin-top: var(--spacing-xs);
}

main {
  background: white;
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow);
  padding: var(--spacing-xl);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: 0.625rem 1.5rem;
  border: none;
  border-radius: var(--border-radius);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 0.15s ease;
}

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

.btn-primary:hover:not(:disabled) {
  background: #002244;
}

.btn-primary:disabled {
  background: var(--text-muted);
  cursor: not-allowed;
}

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

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

.btn-danger:hover:not(:disabled) {
  background: #a01f1f;
}

.error-message,
.success-message {
  border-radius: var(--border-radius);
  padding: var(--spacing-md) var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.error-message {
  background: #fdecea;
  border: 1px solid var(--danger-color);
  color: var(--danger-color);
}

.error-message ul {
  margin: var(--spacing-sm) 0 0 var(--spacing-lg);
}

.success-message {
  background: #eaf6ea;
  border: 1px solid var(--success-color);
  color: var(--success-color);
}

.spinner {
  display: none;
  width: 1rem;
  height: 1rem;
  border: 2px solid rgba(255, 255, 255, 0.4);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

.btn.loading .spinner {
  display: inline-block;
}

.btn.loading .btn-text {
  opacity: 0.7;
}

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

.visually-hidden {
  position: absolute !important;
  left: -9999px;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

/* Admin nav bar */
.admin-nav {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.admin-nav-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--spacing-md);
}

.admin-nav-links {
  display: flex;
  gap: var(--spacing-lg);
  flex-wrap: wrap;
}

.admin-nav-links a {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 600;
}

.admin-nav-links a:hover {
  text-decoration: underline;
}

.admin-user-info {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  color: var(--text-muted);
  font-size: 0.9rem;
}

.role-badge {
  display: inline-block;
  padding: 0.125rem 0.625rem;
  border-radius: 1rem;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--secondary-color);
  color: white;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

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

.modal-content {
  background: white;
  border-radius: var(--border-radius);
  width: 90%;
  max-width: 480px;
  max-height: 90vh;
  overflow-y: auto;
  padding: var(--spacing-xl);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--spacing-lg);
}

.modal-header h2 {
  color: var(--primary-color);
  font-size: 1.25rem;
}

.modal-close {
  background: none;
  border: none;
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  color: var(--text-muted);
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: var(--spacing-md);
  margin-top: var(--spacing-lg);
}

@media (max-width: 768px) {
  .container {
    padding: 0 var(--spacing-md) var(--spacing-xl);
  }

  main {
    padding: var(--spacing-lg);
  }
}