{
  "$schema": "urn:prism:schema:v1:spec",
  "title": "Green for high scores, red for negatives",
  "data": {
    "name": "deltas",
    "values": [
      {"region": "west",    "delta": -0.12},
      {"region": "east",     "delta":  0.34},
      {"region": "north",    "delta":  0.78},
      {"region": "south",    "delta": -0.05},
      {"region": "central",  "delta":  0.18}
    ]
  },
  "mark": "bar",
  "encoding": {
    "x": {"field": "region", "type": "nominal"},
    "y": {"field": "delta",  "type": "quantitative"},
    "color": {
      "condition": [
        {"test": "delta >= 0.5", "value": "#22c55e"},
        {"test": "delta < 0",     "value": "#ef4444"}
      ],
      "value": "#94a3b8"
    }
  }
}