scatter plot of blood pressure measurement with target range

spec.json

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "description": "scatter plot of blood pressure measurement with target range",
  "width": 300,
  "height": 180,
  "padding": {"left": 5, "top": 5, "right": 50, "bottom": 5},
  "data": {
    "values": [
      {"sex": "male", "BP systolic": 120, "BP diastolic": 80, "glucose": 190, "bmi": 28},
      {"sex": "male", "BP systolic": 130, "BP diastolic": 90, "glucose": 95, "bmi": 24},
      {"sex": "male", "BP systolic": 160, "BP diastolic": 110, "glucose": 150, "bmi": 34},
      {"sex": "male", "BP systolic": 175, "BP diastolic": 105, "glucose": 140, "bmi": 34},
      {"sex": "male", "BP systolic": 110, "BP diastolic": 72, "glucose": 90, "bmi": 24},
      {"sex": "male", "BP systolic":  95, "BP diastolic": 68, "glucose": 90, "bmi": 24},
      {"sex": "female", "BP systolic": 145, "BP diastolic": 90, "glucose": 80, "bmi": 28},
      {"sex": "female", "BP systolic": 185, "BP diastolic": 120, "glucose": 140, "bmi": 31},
      {"sex": "female", "BP systolic": 128, "BP diastolic": 85, "glucose": 140, "bmi": 31},
      {"sex": "female", "BP systolic": 115, "BP diastolic": 70, "glucose": 120, "bmi": 16},
      {"sex": "female", "BP systolic": 88, "BP diastolic": 62, "glucose": 90, "bmi": 16},
      {"sex": "female", "BP systolic": 125, "BP diastolic": 80, "glucose": 130, "bmi": 22}
    ]
  },
  "layer": [
    {
      "mark": {
        "type": "rect",
        "fill": "peachpuff",  
        "fillOpacity": 0.1
      },
      "encoding": {
        "x": {"datum": 90 , "scale": {"domain": [80,200]}},
        "x2": {"datum": 140 },
        "y": {"datum": 60 , "scale": {"domain": [50,130]}},
        "y2": {"datum": 90 }
      }
    },
    {
      "mark": {
        "type": "point",
        "filled": true
      },
      "encoding": {
        "x": {
          "field": "BP systolic", 
          "type": "quantitative", 
          "scale": {"domain": [80,200]},
          "axis": {"grid": true}, 
          "title": "Blood Pressure Systolic"
        },
        "y": {
          "field": "BP diastolic", 
          "type": "quantitative" , 
          "scale": {"domain": [50,130]},
          "axis": {"grid": true}, 
          "title": "Blood Pressure Diastolic"
        }
      }
    }
  ]
}