:root {
  /* Color Palette */
  --ui-bg: #f7f9fc;
  --ui-panel: #ffffff;
  --ui-panel-muted: #f2f4f7;
  --ui-border: #e5e7eb;
  --ui-text: #0f172a;
  --ui-text-muted: #64748b;
  --ui-primary: #2563eb;
  --ui-primary-soft: rgba(37, 99, 235, 0.08);
  --ui-success: #16a34a;
  --ui-success-soft: rgba(22, 163, 74, 0.08);
  --ui-warning: #d97706;
  --ui-warning-soft: rgba(217, 119, 6, 0.08);
  --ui-danger: #dc2626;
  --ui-danger-soft: rgba(220, 38, 38, 0.08);
  
  /* Spacing Scale */
  --ui-space-xs: 4px;
  --ui-space-sm: 8px;
  --ui-space-md: 12px;
  --ui-space-lg: 16px;
  --ui-space-xl: 24px;
  --ui-space-2xl: 32px;
  
  /* Typography Scale */
  --ui-text-xs: 0.75rem;
  --ui-text-sm: 0.875rem;
  --ui-text-base: 1rem;
  --ui-text-lg: 1.125rem;
  --ui-text-xl: 1.25rem;
  --ui-text-2xl: 1.5rem;
  --ui-text-3xl: 2rem;
  
  /* Layout */
  --ui-radius: 14px;
  --ui-radius-sm: 8px;
  --ui-radius-lg: 16px;
  --ui-shadow: 0 18px 40px rgba(15, 23, 42, 0.08);
  --ui-shadow-sm: 0 2px 8px rgba(15, 23, 42, 0.06);
  --ui-transition: 150ms ease;
  
  /* Z-index Scale */
  --ui-z-base: 1;
  --ui-z-dropdown: 100;
  --ui-z-sticky: 200;
  --ui-z-modal: 300;
  --ui-z-toast: 400;
}

* {
  box-sizing: border-box;
}

/* Accessibility: Ensure focus is visible for keyboard navigation */
*:focus-visible {
  outline: 2px solid var(--ui-primary);
  outline-offset: 2px;
}

body {
  margin: 0;
  font-family: 'Inter', 'Segoe UI', system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  color: var(--ui-text);
  background: var(--ui-bg);
  min-height: 100vh;
  line-height: 1.6;
}

/* Accessibility: Improve text readability */
h1, h2, h3, h4, h5, h6 {
  line-height: 1.3;
}

/* Accessibility: Ensure links are distinguishable */
a {
  color: var(--ui-primary);
}

a:hover {
  text-decoration: underline;
}

.page {
  background: linear-gradient(135deg, rgba(228, 235, 251, 0.8), var(--ui-bg));
  min-height: 100vh;
}

.top-nav {
  background: #ffffff;
  border-bottom: 1px solid var(--ui-border);
  padding: 18px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: var(--ui-z-sticky);
}

.branding {
  display: flex;
  align-items: center;
  gap: 12px;
}

.branding svg {
  color: var(--ui-primary);
}

.branding strong {
  font-size: 1.1rem;
}

.nav-links {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
}

.nav-links a {
  text-decoration: none;
  color: var(--ui-text-muted);
  padding: 8px 16px;
  border-radius: 999px;
  border: 1px solid transparent;
  transition: var(--ui-transition);
  font-weight: 500;
}

.nav-links a.active,
.nav-links a:hover {
  border-color: var(--ui-primary);
  color: var(--ui-primary);
  background: var(--ui-primary-soft);
}

.nav-links a:focus-visible {
  outline: 2px solid var(--ui-primary);
  outline-offset: 2px;
}

.page-content {
  max-width: 1320px;
  margin: 0 auto;
  padding: 32px 24px 64px;
}

.section-heading {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 18px;
}

.section-heading h2 {
  margin: 0;
  font-size: 1.25rem;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
}

.card {
  background: var(--ui-panel);
  border-radius: var(--ui-radius);
  border: 1px solid var(--ui-border);
  padding: 20px;
  box-shadow: var(--ui-shadow);
}

.card h3 {
  margin-top: 0;
  font-size: 0.95rem;
  color: var(--ui-text-muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.metric-value {
  font-size: 2.2rem;
  margin: 8px 0;
  font-weight: 600;
}

.metric-subtext {
  color: var(--ui-text-muted);
  font-size: 0.9rem;
}

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

.table-card th {
  text-transform: uppercase;
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  color: var(--ui-text-muted);
  border-bottom: 1px solid var(--ui-border);
  padding: 12px;
  text-align: left;
}

.table-card td {
  padding: 14px 12px;
  border-bottom: 1px solid var(--ui-border);
}

.table-card tbody tr:hover {
  background: var(--ui-panel-muted);
  cursor: pointer;
}

.table-card tbody tr:focus-within {
  background: var(--ui-primary-soft);
  outline: 2px solid var(--ui-primary);
  outline-offset: -2px;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  border: 1px solid transparent;
}

.badge.info {
  color: var(--ui-primary);
  border-color: var(--ui-primary);
  background: var(--ui-primary-soft);
}

.badge.success {
  color: var(--ui-success);
  border-color: rgba(22, 163, 74, 0.3);
  background: rgba(22, 163, 74, 0.08);
}

.badge.warning {
  color: var(--ui-warning);
  border-color: rgba(217, 119, 6, 0.3);
  background: rgba(217, 119, 6, 0.08);
}

.badge.danger {
  color: var(--ui-danger);
  border-color: rgba(220, 38, 38, 0.3);
  background: rgba(220, 38, 38, 0.08);
}

.split-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.list li {
  display: flex;
  justify-content: space-between;
  padding: 12px 0;
  border-bottom: 1px solid var(--ui-border);
  font-size: 0.95rem;
}

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

.button-row {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

button.primary,
button.secondary {
  border: none;
  border-radius: 12px;
  padding: 12px 18px;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: transform var(--ui-transition);
}

button.primary {
  background: linear-gradient(120deg, #3b82f6, #2563eb);
  color: #ffffff;
}

button.secondary {
  color: var(--ui-text);
  background: var(--ui-panel-muted);
  border: 1px solid var(--ui-border);
}

button:hover:not(:disabled) {
  transform: translateY(-1px);
}

button:focus-visible {
  outline: 2px solid var(--ui-primary);
  outline-offset: 2px;
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.form-field {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 16px;
}

.form-field label {
  font-size: 0.9rem;
  color: var(--ui-text-muted);
}

.form-field input,
.form-field textarea,
.form-field select {
  border-radius: 12px;
  border: 1px solid var(--ui-border);
  padding: 12px;
  font-size: 0.95rem;
  background: #fff;
  transition: border var(--ui-transition);
}

.form-field input:focus,
.form-field textarea:focus,
.form-field select:focus {
  outline: none;
  border-color: var(--ui-primary);
  box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.15);
}

.ws-stream {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-height: 300px;
  overflow-y: auto;
}

.stream-item {
  border: 1px solid var(--ui-border);
  border-radius: 12px;
  padding: 12px 14px;
  background: var(--ui-panel-muted);
}

.alert {
  border-radius: 12px;
  padding: 12px 16px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.alert.info {
  background: rgba(37, 99, 235, 0.08);
  color: var(--ui-primary);
}

.alert.error {
  background: rgba(220, 38, 38, 0.08);
  color: var(--ui-danger);
}

.empty-state {
  padding: 20px;
  border-radius: 12px;
  text-align: center;
  border: 1px dashed var(--ui-border);
  color: var(--ui-text-muted);
  background: #fff;
}

/* Accessibility: Screen reader only content */
.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;
}

/* Utility: Skip to main content link */
.skip-to-main {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--ui-primary);
  color: white;
  padding: 8px 16px;
  text-decoration: none;
  border-radius: 0 0 8px 0;
  z-index: var(--ui-z-modal);
}

.skip-to-main:focus {
  top: 0;
}

/* Utility Classes */
.text-center {
  text-align: center;
}

.text-muted {
  color: var(--ui-text-muted);
}

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--ui-space-sm); }
.mt-2 { margin-top: var(--ui-space-md); }
.mt-3 { margin-top: var(--ui-space-lg); }
.mt-4 { margin-top: var(--ui-space-xl); }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--ui-space-sm); }
.mb-2 { margin-bottom: var(--ui-space-md); }
.mb-3 { margin-bottom: var(--ui-space-lg); }
.mb-4 { margin-bottom: var(--ui-space-xl); }

.flex {
  display: flex;
}

.flex-col {
  flex-direction: column;
}

.items-center {
  align-items: center;
}

.justify-between {
  justify-content: space-between;
}

.gap-1 { gap: var(--ui-space-sm); }
.gap-2 { gap: var(--ui-space-md); }
.gap-3 { gap: var(--ui-space-lg); }
.gap-4 { gap: var(--ui-space-xl); }

/* Accessibility: Ensure all interactive elements have focus states */
a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible,
select:focus-visible,
[tabindex]:focus-visible {
  outline: 2px solid var(--ui-primary);
  outline-offset: 2px;
}

/* Accessibility: Respect user motion preferences */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Responsive breakpoints */
@media (max-width: 1024px) {
  .card-grid {
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  }

  .split-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .top-nav {
    flex-direction: column;
    gap: 16px;
    padding: 16px 20px;
  }

  .page-content {
    padding: 24px 16px 48px;
  }

  .card-grid {
    grid-template-columns: 1fr;
  }

  .metric-value {
    font-size: 1.8rem;
  }

  .section-heading {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }
}

@media (max-width: 480px) {
  .nav-links {
    width: 100%;
    justify-content: center;
  }

  .button-row {
    flex-direction: column;
  }

  button.primary,
  button.secondary {
    width: 100%;
  }
}