repo.vega

{
  "$schema": "https://vega.github.io/schema/vega/v3.json",
  "autosize": "pad",
  "padding": 5,
  "width": 200,
  "height": 21,
  "title": {"text": "Foo"},
  "style": "cell",
  "data": [{"name": "source"}],
  "marks": [
    {
      "name": "marks",
      "type": "symbol",
      "style": ["point"],
      "from": {"data": "source"},
      "encode": {
        "update": {
          "opacity": {"value": 0.7},
          "fill": {"value": "transparent"},
          "stroke": {"value": "#4c78a8"},
          "x": {"signal": "width", "mult": 0.5},
          "y": {"signal": "height", "mult": 0.5}
        }
      }
    }
  ],
  "config": {
    "axisY": {"minExtent": 30},
    "style": {
      "group-title": {"fontSize": 30, "fontWeight": "bold", "fill": "blue"}
    }
  }
}

repo.vegalite

{
  "config": {
    "title": {
      "color": "blue",
      "fontSize": 30,
      "fontWeight": "bold"
    }
  },
  "title": "Foo",
  "width": 200,
  "mark": "point"
}