:root {
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-border: #e2e8f0;
  --color-text: #1e293b;
  --color-muted: #64748b;
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-accent: #0f766e;
  --color-danger: #dc2626;
  --color-paper: #3b82f6;
  --color-concept: #16a34a;
  --color-tool: #ea580c;
  --color-external: #64748b;
  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, "Cascadia Code", monospace;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(15, 23, 42, 0.08);
  --sidebar-width: 260px;
  --header-height: 56px;
  --footer-height: 40px;
  --sankey-layer-0: #3b82f6;
  --sankey-layer-1: #8b5cf6;
  --sankey-layer-2: #16a34a;
  --sankey-layer-3: #ea580c;
  --sankey-layer-4: #0f766e;
}