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

:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --surface2: #22263a;
  --border: #2e3250;
  --text: #e2e8f0;
  --text-muted: #8892a4;
  --accent: #6366f1;
  --accent-hover: #818cf8;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;

  /* Cell colors */
  --cell-empty: #1a1d27;
  --cell-wall: #0f1117;
  --cell-start: #10b981;
  --cell-end: #ef4444;
  --cell-visited: #312e81;
  --cell-frontier: #4f46e5;
  --cell-path: #fbbf24;
  --cell-border: #2e3250;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  font-size: 14px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 12px 24px;
  display: flex;
  align-items: center;
  gap: 16px;
}

header h1 {
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.5px;
  color: var(--text);
}

header h1 span {
  color: var(--accent);
}

header .subtitle {
  font-size: 12px;
  color: var(--text-muted);
}

.layout {
  display: flex;
  flex: 1;
  overflow: hidden;
}

/* Sidebar */
.sidebar {
  width: 280px;
  flex-shrink: 0;
  background: var(--surface);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.section-title {
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

label {
  font-size: 13px;
  color: var(--text-muted);
  display: flex;
  flex-direction: column;
  gap: 4px;
}

select, input[type="number"], input[type="range"] {
  background: var(--surface2);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 13px;
  outline: none;
  width: 100%;
  transition: border-color 0.15s;
}

select:focus, input[type="number"]:focus {
  border-color: var(--accent);
}

select option {
  background: var(--surface2);
}

input[type="range"] {
  padding: 4px 0;
  cursor: pointer;
  accent-color: var(--accent);
}

.btn-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

button {
  padding: 8px 14px;
  border-radius: 6px;
  border: none;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.15s, opacity 0.15s;
  width: 100%;
  text-align: center;
}

button:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover:not(:disabled) { background: var(--accent-hover); }

.btn-secondary {
  background: var(--surface2);
  color: var(--text);
  border: 1px solid var(--border);
}
.btn-secondary:hover:not(:disabled) { border-color: var(--accent); color: var(--accent); }

.btn-danger {
  background: transparent;
  color: var(--danger);
  border: 1px solid var(--danger);
}
.btn-danger:hover:not(:disabled) { background: var(--danger); color: #fff; }

/* Stats */
.stats-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.stat-card {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 12px;
}

.stat-value {
  font-size: 22px;
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
}

.stat-label {
  font-size: 10px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-top: 4px;
}

/* Legend */
.legend {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-muted);
}

.legend-dot {
  width: 14px;
  height: 14px;
  border-radius: 3px;
  flex-shrink: 0;
}

/* Instructions */
.instructions {
  font-size: 12px;
  color: var(--text-muted);
  line-height: 1.6;
}

.instructions kbd {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 1px 5px;
  font-size: 11px;
  font-family: monospace;
  color: var(--text);
}

/* Status bar */
#status-bar {
  font-size: 12px;
  padding: 6px 10px;
  border-radius: 6px;
  background: var(--surface2);
  border: 1px solid var(--border);
  color: var(--text-muted);
  min-height: 32px;
  display: flex;
  align-items: center;
}

#status-bar.running { border-color: var(--accent); color: var(--accent); }
#status-bar.done    { border-color: var(--success); color: var(--success); }
#status-bar.error   { border-color: var(--danger);  color: var(--danger);  }

/* Main grid area */
.main {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  overflow: auto;
}

#grid-container {
  display: inline-block;
  border: 2px solid var(--border);
  border-radius: 4px;
  overflow: hidden;
  line-height: 0;
  cursor: crosshair;
  user-select: none;
}

canvas#grid-canvas {
  display: block;
}

/* Benchmark modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
}

.modal-overlay.hidden { display: none; }

.modal {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  width: 560px;
  max-width: 95vw;
  max-height: 90vh;
  overflow-y: auto;
}

.modal h2 {
  margin-bottom: 16px;
  font-size: 16px;
}

.modal-close {
  float: right;
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 20px;
  cursor: pointer;
  width: auto;
  padding: 0;
  line-height: 1;
}

.bench-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
}

.bench-table th {
  text-align: left;
  padding: 8px 10px;
  border-bottom: 1px solid var(--border);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.bench-table td {
  padding: 8px 10px;
  border-bottom: 1px solid var(--border);
}

.bench-table tr:last-child td { border-bottom: none; }

.bench-bar-wrap {
  background: var(--surface2);
  border-radius: 3px;
  height: 8px;
  width: 120px;
  overflow: hidden;
}

.bench-bar {
  height: 100%;
  background: var(--accent);
  border-radius: 3px;
  transition: width 0.4s;
}

.speed-label {
  font-size: 11px;
  color: var(--text-muted);
  text-align: right;
}

@media (max-width: 700px) {
  .layout { flex-direction: column; }
  .sidebar { width: 100%; border-right: none; border-bottom: 1px solid var(--border); }
  .main { padding: 12px; }
}