<div id="map"></div>

html, body {
  height: 100%;
  margin: 0;
}

#map {
  height: 100%;
}

.leaflet-container .leaflet-tile-pane img {
  filter: grayscale(1);
}

var map = L.map('map');

var tileLayer = L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
  attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
});

tileLayer.addTo(map);

map.setView([55,	-2], 6);