:root {
  --bg: #0e0f12;
  --fg: #e5e7eb;
  --muted: #9ca3af;
  --lA: #ef4444; /* 红 A */
  --lB: #f59e0b; /* 橙 B */
  --lC: #60a5fa; /* 蓝 C */
  --lD: #22c55e; /* 绿 D */
  --panel: #1f2430;
  /* 画布标记用的 1/2/3 级颜色（缺失会导致黑色） */
  --l1: #60a5fa; /* 低级：蓝 */
  --l2: #f59e0b; /* 中级：橙 */
  --l3: #ef4444; /* 高级：红 */
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--fg);
  background: radial-gradient(1200px 1200px at 10% 10%, #121722, var(--bg));
}

.app-header {
  padding: 16px 20px;
  background: rgba(0,0,0,.35);
  border-bottom: 1px solid rgba(255,255,255,.08);
  position: sticky;
  top: 0;
  backdrop-filter: blur(6px);
  z-index: 10;
}
.app-header h1 { margin: 0 0 8px; font-size: 20px; }
.controls { display: flex; flex-wrap: wrap; gap: 10px 16px; align-items: center; }
.control { display: flex; gap: 8px; align-items: center; }
.hints { margin-top: 8px; color: var(--muted); font-size: 12px; }

.stage { display: grid; grid-template-columns: 1fr 280px; gap: 16px; padding: 16px; }
.canvas-wrap { width: 100%; display: grid; place-items: center; }

#canvas {
  background: #0b0d12;
  border: 1px solid rgba(255,255,255,.08);
  border-radius: 8px;
  max-width: 100%;
}

.sidebar { background: rgba(0,0,0,.25); border: 1px solid rgba(255,255,255,.08); border-radius: 8px; padding: 12px; }
.legend ul { list-style: none; padding: 0; margin: 8px 0 0; display: grid; gap: 8px; }
.dot { display: inline-block; width: 12px; height: 12px; border-radius: 50%; margin-right: 6px; vertical-align: -1px; }
.dot.lA { background: var(--lA); }
.dot.lB { background: var(--lB); }
.dot.lC { background: var(--lC); }
.dot.lD { background: var(--lD); }

.stats { margin-top: 12px; background: var(--panel); border-radius: 6px; padding: 10px; font-size: 13px; }
.legend-editor { margin-top: 12px; }
.legend-form { display: grid; gap: 8px; }
.legend-form label { display: grid; grid-template-columns: 28px 1fr; align-items: center; gap: 8px; }
.legend-form input { width: 100%; padding: 6px 8px; border-radius: 6px; border: 1px solid rgba(255,255,255,.1); background: #2b3342; color: var(--fg); }

.footer { color: var(--muted); font-size: 12px; padding: 12px 16px; }

button { cursor: pointer; background: #2b3342; color: var(--fg); border: 1px solid rgba(255,255,255,.1); padding: 6px 10px; border-radius: 6px; }
button:hover { background: #3a4356; }

@media (max-width: 960px) {
  .stage { grid-template-columns: 1fr; }
}