:root {
  --bg: #f5f6f8;
  --panel: #ffffff;
  --border: #d8dde3;
  --text: #202827;
  --muted: #6b7a78;
  --accent: #087c6c;
  --accent-light: #dcefe9;
  --highlight: #fff4db;
  --danger: #b9472f;
  --danger-light: #fbe3dd;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
}

header {
  padding: 16px 24px;
  background: var(--panel);
  border-bottom: 1px solid var(--border);
}

header h1 { margin: 0; font-size: 22px; }
header .subtitle { margin: 6px 0 0; color: var(--muted); font-size: 14px; }

main { padding: 16px 24px 32px; }

.control-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-bottom: 16px;
}

.control-bar label { font-size: 14px; color: var(--muted); display: inline-flex; align-items: center; gap: 6px; }

.control-bar input[type="number"] {
  width: 64px;
  padding: 4px 6px;
  font-size: 15px;
  border: 1px solid var(--border);
  border-radius: 4px;
}

button {
  padding: 6px 14px;
  font-size: 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--panel);
  cursor: pointer;
  color: var(--text);
}

button:hover { border-color: var(--accent); color: var(--accent); }
button:disabled { opacity: 0.45; cursor: not-allowed; }

button#btn-play.running { background: var(--danger-light); border-color: var(--danger); color: var(--danger); }

.speed-label { display: inline-flex; align-items: center; gap: 6px; }
.speed-label input { width: 110px; }

.step-info { margin-left: auto; font-size: 14px; color: var(--muted); font-variant-numeric: tabular-nums; }

.stage {
  display: grid;
  grid-template-columns: minmax(590px, 1.1fr) minmax(0, 0.9fr);
  gap: 16px;
}

.canvas-panel, .code-panel {
  min-width: 0;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
}

.canvas-panel h2, .code-panel h2 { margin: 0 0 10px; font-size: 15px; }

#canvas {
  display: block;
  width: 100%;
  height: auto;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 6px;
}

.found-list { margin-top: 12px; }

.found-list ol {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 8px 0 0;
  padding: 0;
}

.found-list li {
  padding: 4px 10px;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: 999px;
  font-size: 14px;
  font-variant-numeric: tabular-nums;
}

.code-panel pre {
  width: 100%;
  max-width: 100%;
  margin: 0;
  font-size: 14px;
  line-height: 1.55;
  border-radius: 6px;
  overflow: auto;
  max-height: 540px;
}

#code-block { display: block; }

.code-line {
  display: block;
  white-space: pre;
  min-height: 1.55em;
  padding: 0 10px;
  border-left: 3px solid transparent;
}

.code-line.cur-line {
  background: var(--highlight);
  border-left-color: #b76e00;
}

.note {
  margin-top: 12px;
  min-height: 28px;
  padding: 8px 12px;
  border-radius: 6px;
  font-size: 14px;
  border-left: 4px solid var(--accent);
  background: var(--accent-light);
}

.note.forward { border-color: var(--accent); background: var(--accent-light); }
.note.backtrack { border-color: var(--danger); background: var(--danger-light); }
.note.boundary { border-color: #b76e00; background: #fff4db; }
.note.plain { border-color: var(--border); background: #f1f3f5; }

@media (max-width: 1050px) {
  .stage { grid-template-columns: 1fr; }
}