const String mapStyle = '''
[
  { "featureType": "all",            "elementType": "labels",           "stylers":[{"visibility":"off"}] },
  { "featureType": "all",            "elementType": "geometry",         "stylers":[{"visibility":"off"}] },

  { "featureType": "road",           "elementType": "geometry.fill",    "stylers":[{"visibility":"on"},{"color":"#ffffff"}] },
  { "featureType": "road",           "elementType": "geometry.stroke",  "stylers":[{"visibility":"off"}] }
]
''';