d3.carto lesson from MaptimeSF

<html xmlns="https://www.w3.org/1999/xhtml">
<head>
  <title>d3.carto - Simple Map Example</title>
  <meta charset="utf-8" />
    <link type="text/css" rel="stylesheet" href="d3map.css" />
</head>
<style>
  html,body {
    height: 100%;
    width: 100%;
    margin: 0;
  }

#map {
    height: 100%;
    width: 100%;
    position: absolute;
  }

.country {
     fill-opacity: 1;
     fill: #4682B4;
     stroke-opacity: 1;
     stroke: black;
     stroke-width: 2px;
  }

</style>
<script>
function makeSomeMaps() {
    map = d3.carto.map();

d3.select("#map").call(map);

countryLayer = d3.carto.layer.geojson();

countryLayer.path("world.geojson")
    .label("Countries")
    .renderMode("svg")
    .clickableFeatures(true)
    .cssClass("country");

map.addCartoLayer(countryLayer);
    map.setScale(2);
    map.mode("projection");

}
</script>
<body onload="makeSomeMaps()">
<div id="map"></div>
<footer>
<script src="https://d3js.org/d3.v3.min.js" charset="utf-8" type="text/javascript"></script>
<script src="d3.carto.map.js" type="text/javascript">
</script>
</footer>
</body>
</html>

Modified http://d3js.org/d3.v3.min.js to a secure url

https://d3js.org/d3.v3.min.js