let map = null;
let mapImg = null;

function initializeMap(mapImgUrl) {
  if (!map) {
    map = L.map('map', { minZoom: 0, maxZoom: 4, crs: L.CRS.Simple });
  }
  if (mapImg) {
    mapImg.removeFrom(map);
  }
  mapImg = L.imageOverlay(mapImgUrl, [[-180, 180],[180, -180]]);
  mapImg.addTo(map);
  map.setMaxBounds([[-180,180],[180,-180]]);
  map.setView([0,0], 2);
}