<!DOCTYPE html>
<html>
  <head>
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link rel="stylesheet" href="https://unpkg.com/leaflet@1.0./dist/leaflet.css" />
    <style>
      #map {
        bottom: 0;
        left: 0;
        position: absolute;
        right: 0;
        top: 0;
      }
    </style>
  </head>
  <body>
    <div id="map"></div>
    <script src="https://unpkg.com/browse/whatwg-fetch@3.2.0/dist/fetch.umd.js"></script>
    <script src="https://unpkg.com/leaflet