style.json

{
  "version":8,
  "name": "maria",
  "sources": {
    "mapbox": {
      "type": "vector",
      "url": "mapbox://mapbox.mapbox-streets-v7"
    },
    "drifters": {
      "type":"geojson",
      "data":"datasets/drifters.geojson"
    }
  },
  "layers": [
    {
      "id": "background",
      "type": "background",
      "paint": {
          "background-color": "#cccccc"
      }
    },
    {
        "id": "water",
        "type": "fill",
        "source": "mapbox",
        "source-layer": "water",
        "paint": {
            "fill-color": "#222222"
        }
    },
    {
        "id": "drifters",
        "type": "circle",
        "source": "drifters",
        "paint": {
            "circle-radius":2,
            "circle-color": ["case",
                ["all",
                  [">=",["to-number",["get","timestamp"]],1505574000000],
                  ["<=",["to-number",["get","timestamp"]],1506805200000]
                ],"red","green"],
            "circle-opacity":0.1
        }
    }
  ]
}