<style>
#map {
height: 350px;
position: relative;
width: 100%;
}
</style>
<div id="map"></div>
<script>
var NPMap = {
div: 'map',
legendControl: {
html: '<h3>Legend</h3><ul><li>Item 1</li><li>Item 2</li></ul>'
}
};
(function () {
var s = document.createElement('script');
s.src = 'https://www.nps.gov/lib/npmap.js/4.0.0/npmap-bootstrap.js';
document.body.appendChild(s);
})();
</script>