:root {
  --bg-color: #f8fafc;
  --card-bg: #ffffff;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --primary-color: #4f46e5;
  --primary-hover: #4338ca;
  --border-color: #e2e8f0;
  --card-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1);
  --ul-color: #e0f2fe;
  --ul-border: #7dd3fc;
  --ul-text: #0369a1;
  --lr-color: #fef3c7;
  --lr-border: #fcd34d;
  --lr-text: #b45309;
  --ur-color: #e0f2fe;
  --ur-border: #7dd3fc;
  --ur-text: #0369a1;
  --ll-color: #fef3c7;
  --ll-border: #fcd34d;
  --ll-text: #b45309;
  --blk-color: #94a3b8;
  --blk-border: #334155;
}

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

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

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem;
}

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

header h1 {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.3rem;
  letter-spacing: -0.02em;
}

.subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
}

/* Tabs */
.tabs-nav {
  display: flex;
  gap: 0.5rem;
  border-bottom: 2px solid var(--border-color);
  margin-bottom: 2rem;
}

.tab-button {
  background: none;
  border: none;
  padding: 0.75rem 1.25rem;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  border-bottom: 3px solid transparent;
  margin-bottom: -2px;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: all 0.2s ease;
}

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

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

.badge {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  background-color: #f1f5f9;
  color: #64748b;
  padding: 0.2rem 0.5rem;
  border-radius: 9999px;
  border: 1px solid #cbd5e1;
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

/* Grid layout for cards */
.card-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

@media (max-width: 850px) {
  .card-grid {
    grid-template-columns: 1fr;
  }
}

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

.card h2 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1.25rem;
}

.card-header-tabs {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.card-header-tabs h2 {
  margin-bottom: 0;
}

.view-toggle {
  display: flex;
  background-color: #f1f5f9;
  border-radius: 8px;
  padding: 2px;
}

.toggle-btn {
  border: none;
  background: transparent;
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.35rem 0.65rem;
  border-radius: 6px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}

.toggle-btn.active {
  background: white;
  color: var(--primary-color);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}

/* Form inputs */
.form-group {
  margin-bottom: 1.25rem;
}

.form-group label {
  display: block;
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 0.4rem;
}

.highlight-val {
  color: var(--primary-color);
  font-size: 1.15rem;
  margin-left: 0.25rem;
}

.slider-row {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.slider-row input[type="range"] {
  flex: 1;
  cursor: pointer;
}

.slider-row input[type="number"] {
  width: 60px;
  padding: 0.4rem 0.5rem;
  font-size: 1rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  text-align: center;
}

.helper-text {
  display: block;
  font-size: 0.825rem;
  color: var(--text-secondary);
  margin-top: 0.35rem;
}

/* Stats Box */
.stats-box {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.75rem;
  background-color: #f8fafc;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1rem;
  margin-bottom: 1.25rem;
}

@media (max-width: 500px) {
  .stats-box {
    grid-template-columns: 1fr;
  }
}

.stat-item {
  display: flex;
  flex-direction: column;
  text-align: center;
}

.stat-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
  font-weight: 600;
}

.stat-value {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0.2rem 0;
}

.stat-desc {
  font-size: 0.75rem;
  color: #64748b;
}

/* Options */
.options-group {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
}

.ingrid-hint {
  background-color: #eff6ff;
  border: 1px solid #bfdbfe;
  border-radius: 6px;
  padding: 0.75rem 1rem;
  font-size: 0.85rem;
  color: #1e40af;
  margin-top: 1rem;
}

.ingrid-hint code {
  display: block;
  background-color: #dbeafe;
  padding: 0.3rem 0.5rem;
  border-radius: 4px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  margin-top: 0.35rem;
  user-select: all;
}

/* Grid Visualizer */
.grid-container {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 240px;
  padding: 0.5rem;
  background-color: #f8fafc;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  overflow-x: auto;
}

.puzzle-grid {
  display: grid;
  gap: 2px;
  background-color: #cbd5e1;
  padding: 2px;
  border-radius: 4px;
}

.puzzle-cell {
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.65rem;
  font-weight: 700;
  border-radius: 2px;
  cursor: pointer;
  transition: transform 0.1s ease, filter 0.1s ease;
  user-select: none;
}

.puzzle-cell:hover {
  transform: scale(1.15);
  z-index: 5;
  filter: brightness(0.92);
}

.cell-ul,
.cell-ur {
  background-color: var(--ul-color);
  color: var(--ul-text);
  border: 1px solid var(--ul-border);
}

.cell-lr,
.cell-ll {
  background-color: var(--lr-color);
  color: var(--lr-text);
  border: 1px solid var(--lr-border);
}

.cell-blk {
  background-color: var(--blk-color);
  border: 1px solid var(--blk-border);
  cursor: default;
}
.cell-blk:hover {
  transform: none;
}

.cell-void {
  background: transparent;
  border: none;
  cursor: default;
}
.cell-void:hover {
  transform: none;
}

.grid-legend {
  display: flex;
  justify-content: center;
  gap: 1.25rem;
  margin-top: 0.75rem;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.legend-color {
  width: 14px;
  height: 14px;
  border-radius: 3px;
  display: inline-block;
}

.legend-ul,
.legend-ur {
  background-color: var(--ul-color);
  border: 1px solid var(--ul-border);
}

.legend-lr,
.legend-ll {
  background-color: var(--lr-color);
  border: 1px solid var(--lr-border);
}

.legend-blk {
  background-color: var(--blk-color);
  border: 1px solid var(--blk-border);
}

.cell-info-display {
  text-align: center;
  font-size: 0.8rem;
  color: var(--primary-color);
  font-weight: 600;
  margin-top: 0.4rem;
  min-height: 1.2rem;
}

/* Output Card */
.output-card {
  display: flex;
  flex-direction: column;
}

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

.output-actions {
  display: flex;
  gap: 0.5rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.875rem;
  font-weight: 600;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.2s ease;
}

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

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

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

.btn-secondary:hover {
  background-color: #f1f5f9;
}

textarea#batch-output {
  width: 100%;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.875rem;
  line-height: 1.45;
  color: #1e293b;
  background-color: #f8fafc;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1rem;
  resize: vertical;
  box-sizing: border-box;
  white-space: pre;
}

.text-input {
  width: 100%;
  padding: 0.5rem 0.75rem;
  font-size: 0.95rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  outline: none;
  box-sizing: border-box;
}

.text-input:focus {
  border-color: var(--primary-color);
}

textarea#ipuz-solution-input,
textarea#ipuz-clues-input,
textarea#ipuz-json-output,
textarea#multi-clues-input,
textarea#multi-ipuz-json-output,
.subgrid-input-box textarea {
  width: 100%;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.875rem;
  line-height: 1.45;
  color: #1e293b;
  background-color: #f8fafc;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.85rem;
  resize: vertical;
  box-sizing: border-box;
}

.subgrid-inputs-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
}

@media (max-width: 768px) {
  .subgrid-inputs-grid {
    grid-template-columns: 1fr;
  }
}

.subgrid-input-box {
  background-color: #f8fafc;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1rem;
  display: flex;
  flex-direction: column;
}

.subgrid-input-box label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.25rem;
}

.subgrid-badge {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  background-color: #e2e8f0;
  color: #475569;
  padding: 0.15rem 0.45rem;
  border-radius: 4px;
}

.status-indicator {
  font-size: 0.85rem;
  margin-top: 0.5rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.status-indicator.status-ok {
  color: #16a34a;
}

.status-indicator.status-warn {
  color: #d97706;
}

.status-indicator.status-error {
  color: #dc2626;
}

footer {
  text-align: center;
  font-size: 0.85rem;
  color: #94a3b8;
  margin-top: 3rem;
}