:root {
  color-scheme: light;
  font-family: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
  font-size: 16px;
  --page-bg: #f4f6fb;
  --surface-color: #ffffff;
  --surface-muted: #f8fafc;
  --surface-emphasis: #eef1f7;
  --header-bg: #1f2937;
  --footer-bg: #111827;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --text-inverse: #f8fafc;
  --accent: #4f46e5;
  --accent-strong: #4338ca;
  --accent-soft: rgba(79, 70, 229, 0.1);
  --accent-outline: rgba(79, 70, 229, 0.35);
  --border-color: rgba(15, 23, 42, 0.08);
  --border-muted: rgba(148, 163, 184, 0.2);
  --border-strong: rgba(79, 70, 229, 0.3);
  --radius-lg: 0.75rem;
  --radius-md: 0.5rem;
  --radius-sm: 0.375rem;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.05);
  --shadow-md: 0 4px 6px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 10px 15px rgba(15, 23, 42, 0.1);
  --info-bg: rgba(148, 163, 184, 0.1);
  --info-border: rgba(148, 163, 184, 0.3);
  --success-bg: rgba(34, 197, 94, 0.1);
  --success-border: rgba(34, 197, 94, 0.4);
  --error-bg: rgba(248, 113, 113, 0.1);
  --error-border: rgba(248, 113, 113, 0.4);
  --badge-valid-bg: rgba(34, 197, 94, 0.15);
  --badge-valid-text: #065f46;
  --badge-invalid-bg: rgba(248, 113, 113, 0.15);
  --badge-invalid-text: #7f1d1d;
  --outline-offset: 2px;
}

@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --page-bg: #030712;
    --surface-color: #0f172a;
    --surface-muted: #1e293b;
    --surface-emphasis: #0b1324;
    --header-bg: #0b1324;
    --footer-bg: #050b19;
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --text-inverse: #f9fafb;
    --accent-soft: rgba(99, 102, 241, 0.15);
    --border-color: rgba(148, 163, 184, 0.1);
    --border-muted: rgba(148, 163, 184, 0.2);
    --border-strong: rgba(99, 102, 241, 0.4);
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
    --info-bg: rgba(148, 163, 184, 0.15);
    --info-border: rgba(148, 163, 184, 0.3);
    --success-bg: rgba(34, 197, 94, 0.15);
    --success-border: rgba(34, 197, 94, 0.4);
    --error-bg: rgba(248, 113, 113, 0.15);
    --error-border: rgba(248, 113, 113, 0.4);
    --badge-valid-bg: rgba(34, 197, 94, 0.2);
    --badge-valid-text: #86efac;
    --badge-invalid-bg: rgba(248, 113, 113, 0.2);
    --badge-invalid-text: #fca5a5;
  }
}

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

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

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--page-bg);
  color: var(--text-primary);
}

code {
  font-family: "JetBrains Mono", "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  padding: 0.1rem 0.35rem;
  border-radius: var(--radius-sm);
  background: var(--surface-emphasis);
  color: var(--text-secondary);
}

.app-header,
.app-footer {
  padding: 2rem;
  color: var(--text-inverse);
}

.app-header {
  background: var(--header-bg);
  border-bottom: 1px solid rgba(15, 23, 42, 0.2);
}

.app-header h1 {
  margin: 0 0 0.5rem;
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.tagline {
  margin: 0;
  font-size: 0.95rem;
  color: rgba(248, 250, 252, 0.85);
}

.app-footer {
  margin-top: auto;
  font-size: 0.875rem;
  text-align: center;
  background: var(--footer-bg);
  border-top: 1px solid rgba(15, 23, 42, 0.2);
}

.app-main {
  flex: 1;
  padding: 2rem;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
}

.app-shell {
  display: flex;
  gap: 2rem;
  align-items: flex-start;
}

.sidebar {
  width: 320px;
  flex-shrink: 0;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  position: sticky;
  top: 2rem;
}

.content {
  flex: 1;
  min-width: 0;
}

.panel {
  background: var(--surface-color);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-md);
  padding: 1.5rem;
  display: grid;
  gap: 1.25rem;
}

.panel-heading h2 {
  margin: 0 0 0.25rem;
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
}

.panel-heading p {
  margin: 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.control-group {
  display: grid;
  gap: 0.5rem;
}

.control-label {
  font-weight: 600;
  font-size: 0.875rem;
  color: var(--text-primary);
}

.control-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 0.75rem;
  align-items: center;
}

.control-help {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.divider {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 600;
}

.divider::before,
.divider::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border-muted);
}

.select,
.file-input,
.button {
  font: inherit;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-muted);
  padding: 0.625rem 0.875rem;
  transition: all 0.15s ease;
}

.select {
  width: 100%;
  background: var(--surface-color);
  color: var(--text-primary);
}

.file-input {
  width: 100%;
  background: var(--surface-color);
  color: var(--text-primary);
}

.select:focus-visible,
.file-input:focus-visible {
  outline: 3px solid var(--accent-outline);
  outline-offset: var(--outline-offset);
}

.file-input {
  cursor: pointer;
}

.file-input::file-selector-button,
.file-input::-webkit-file-upload-button {
  font: inherit;
  border: none;
  margin-right: 0.75rem;
  padding: 0.5rem 0.875rem;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: var(--text-inverse);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
}

.file-input::file-selector-button:hover,
.file-input::-webkit-file-upload-button:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.button {
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  border: none;
  color: var(--text-inverse);
  cursor: pointer;
  font-weight: 600;
  font-size: 0.875rem;
  white-space: nowrap;
  box-shadow: var(--shadow-sm);
}

.button:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

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

.button:disabled {
  background: var(--surface-emphasis);
  color: var(--text-muted);
  border: 1px solid var(--border-muted);
  cursor: not-allowed;
  box-shadow: none;
  transform: none;
  opacity: 0.6;
}

.button-secondary {
  background: var(--surface-muted);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  box-shadow: none;
}

.button-secondary:hover:not(:disabled) {
  background: var(--surface-emphasis);
  box-shadow: var(--shadow-sm);
}

.current-selection {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  background: var(--accent-soft);
  border: 1px solid var(--border-strong);
  font-size: 0.875rem;
}

.current-selection-label {
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  font-size: 0.7rem;
  color: var(--text-muted);
}

.current-selection-value {
  font-weight: 600;
  color: var(--text-primary);
}

.panel-status {
  gap: 1rem;
}

.status-header {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 1rem;
}

.dataset-info {
  font-weight: 600;
  color: var(--text-primary);
  font-size: 0.875rem;
  flex: 1;
}

.nav-buttons {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
  min-width: 140px;
}

.progress {
  width: 100%;
  height: 0.5rem;
  border-radius: 999px;
  background: rgba(148, 163, 184, 0.2);
  overflow: hidden;
  appearance: none;
}

.progress::-webkit-progress-bar {
  background: transparent;
}

.progress::-webkit-progress-value {
  background: linear-gradient(90deg, var(--accent), var(--accent-strong));
  border-radius: 999px;
  transition: width 0.3s ease;
}

.progress::-moz-progress-bar {
  background: linear-gradient(90deg, var(--accent), var(--accent-strong));
  border-radius: 999px;
  transition: width 0.3s ease;
}

.progress.is-empty::-webkit-progress-value,
.progress.is-empty::-moz-progress-bar {
  background: transparent;
}

.message {
  padding: 1rem;
  border-radius: var(--radius-md);
  background: var(--info-bg);
  color: var(--text-primary);
  font-weight: 500;
  border: 1px solid var(--info-border);
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.9rem;
  line-height: 1.5;
}

.message::before {
  content: "ℹ";
  font-weight: 600;
  font-size: 1rem;
  color: inherit;
  background: rgba(148, 163, 184, 0.3);
  border-radius: 50%;
  width: 1.5rem;
  height: 1.5rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.message[data-type="error"] {
  background: var(--error-bg);
  color: #991b1b;
  border-color: var(--error-border);
}

.message[data-type="success"] {
  background: var(--success-bg);
  color: #166534;
  border-color: var(--success-border);
}

.message[data-type="error"]::before {
  content: "✕";
  background: rgba(248, 113, 113, 0.3);
}

.message[data-type="success"]::before {
  content: "✓";
  background: rgba(34, 197, 94, 0.3);
}

.record-card {
  background: var(--surface-color);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-lg);
  padding: 2rem;
  display: grid;
  gap: 1.5rem;
}

.record-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.record-title-group {
  display: grid;
  gap: 0.5rem;
}

.record-subtitle {
  margin: 0;
  text-transform: uppercase;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--text-muted);
}

.question-title {
  margin: 0;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
  line-height: 1.3;
}

.badge {
  padding: 0.5rem 1rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  background: var(--surface-muted);
  color: var(--text-muted);
  border: 1px solid var(--border-color);
}

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

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

.meta-grid {
  display: grid;
  gap: 0.75rem;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
}

.meta-chip {
  display: grid;
  gap: 0.375rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--surface-muted);
}

.meta-chip[data-empty="true"] {
  opacity: 0.72;
  border-style: dashed;
}

.meta-chip[data-empty="true"] .meta-value {
  color: var(--text-muted);
  font-style: italic;
}

.meta-label {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
}

.meta-value {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.record-grid {
  display: grid;
  gap: 1.25rem;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.block {
  padding: 1.25rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--surface-muted);
  display: grid;
  gap: 0.75rem;
}

.block h3 {
  margin: 0;
  font-size: 0.875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
}

.block--wide {
  grid-column: 1 / -1;
  background: var(--accent-soft);
  border-color: var(--border-strong);
}

.text-block {
  margin: 0;
  line-height: 1.6;
  white-space: pre-wrap;
}

.text-block.is-empty {
  color: var(--text-muted);
  font-style: italic;
}

.options-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 0.75rem;
}

.options-list li {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--surface-color);
  box-shadow: var(--shadow-sm);
  line-height: 1.5;
  display: flex;
  gap: 0.5rem;
  align-items: baseline;
  color: var(--text-primary);
}

.options-list li.is-correct {
  border-color: var(--success-border);
  background: var(--success-bg);
  font-weight: 500;
}

.options-list .option-key {
  font-weight: 600;
  margin-right: 0.5rem;
  color: var(--accent-strong);
  flex-shrink: 0;
}

.options-list li .is-empty {
  color: var(--text-muted);
  font-style: italic;
}

.options-list.is-empty {
  gap: 0;
}

.option-empty-message {
  justify-content: center;
  font-style: italic;
  color: var(--text-muted);
  background: var(--surface-muted);
  border-style: dashed;
}

.definition-list {
  margin: 0;
  display: grid;
  gap: 0.75rem;
}

.definition-list dt {
  font-weight: 600;
  font-size: 0.875rem;
  color: var(--text-primary);
}

.definition-list dd {
  margin: 0 0 0 0;
  line-height: 1.6;
  color: var(--text-secondary);
}

.hidden {
  display: none !important;
}

@media (max-width: 960px) {
  .app-shell {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
    position: static;
  }

  .app-main {
    padding: 1.5rem;
  }
}

@media (max-width: 640px) {
  .app-header,
  .app-footer {
    padding: 1.5rem;
  }

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

  .app-main {
    padding: 1rem;
  }

  .panel {
    padding: 1.25rem;
  }

  .record-card {
    padding: 1.5rem;
  }

  .status-header {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }

  .nav-buttons {
    grid-template-columns: 1fr 1fr;
    width: 100%;
  }

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

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

  .record-subtitle {
    font-size: 0.7rem;
  }

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