<div id="map"></div>
<script>
var map = new mapboxgl.Map({
    container: "map",
    style: "mapbox://styles/mapbox/outdoors-v9",
    center: [-121.403732, 40.492392],
    zoom: 10
});

map.on("load", function() {
    map.addSource("national-park", {
        "type": "geojson",
        "data": {
            "type": "FeatureCollection",
            "features": [{
                "type": "Feature",
                "geometry": {
                    "type": "Polygon",
                    "coordinates": [
       