Responsive US state choropleth

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  font-family: 'Proxima Nova', sans-serif;
}

.g-hed {
  text-align: left;
  text-transform: uppercase;
  font-weight: bold;
  font-size:22px; 
  margin: 3px 0;
}

.g-source-bold {
  text-align: left;
  font-size:10px;
  font-weight: bold; 
}

.g-source-reg {
  text-align: left;
  font-size:10px; 
}

.g-source {
  margin: 10px 0;
}

.g-intro {
  font-size: 16px;
  margin: 0px 0px 10px 0px;
}

.states {
  fill: #d3d3d3;
  stroke: #ffffff;
  stroke-linejoin: round;
}

.q0-9 { fill: #d9e0f2; }
.q1-9 { fill: #99b2dc; }
.q2-9 { fill: #5e8dc9; }
.q3-9 { fill: #2f5491; }
.q4-9 { fill: #0e2344; }

#q0-9 { background-color: #d9e0f2; }
#q1-9 { background-color: #99b2dc; }
#q2-9 { background-color: #5e8dc9; }
#q3-9 { background-color: #2f5491; }
#q4-9 { background-color: #0e2344; }

div.tooltip {
  position: absolute;
  left: 75px;
  text-align: center;
  height: 12px;
  padding: 8px;
  font-size: 13px;
  font-family: 'Proxima-Nova', sans-serif;
  background: #FFFFFF;
  border: 1px solid #989898;
  pointer-events: none;
}

.block {
  width:18%;
  height: 15px;
  display:inline-block;
}

</style>
<body>
  <h5 class="g-hed"></h5>
  <p class="g-intro"></p>
  <div class="g-chart"></div>
    <div class="legend">
    <div class="block" id="q0-9"></div>
    <div class="block" id="q1-9"></div>
    <div class="block" id="q2-9"></div>
    <div class="block" id="q3-9"></div>
    <div class="block" id="q4-9"></div>
  </div>
  <div class="g-source"><span class="g-source-bold"></span><span class="g-source-reg"></span></div>
</body>  
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/queue-async/1.0.7/queue.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/topojson/1.6.19/topojson.min.js"></script>

//Creates tooltip and makes it invisiblae
var div = d3.select("body").append("div")
  .attr("class", "tooltip")
  .style("opacity", 0);

//Sets dimensions
var margin = {top: 10, left: 10, bottom: 10, right: 10}
  , width = window.outerWidth
  , width = width - margin.left - margin.right
  , mapRatio = .5
  , height = width * mapRatio;

//Tells the nap what projection to use
var projection = d3.geo.albersUsa()
    .scale(width)
    .translate([width / 2, height / 2]);

//Tells the map how to draw the paths from the projection
var path = d3.geo.path()
    .projection(projection);

//Appened svg to page
var map = d3.select(".g-chart").append("svg")
  .style('height', height + 'px')
  .style('width', width + 'px');

//Load the files
queue()
    .defer(d3.json, "us.json")
    .defer(d3.csv, "maptemplate.csv")
    .await(ready);

//Moves selection to front
d3.selection.prototype.moveToFront = function() {
  return this.each(function(){
    this.parentNode.appendChild(this);
  });
};

//Moves selection to back
d3.selection.prototype.moveToBack = function() { 
  return this.each(function() { 
  var firstChild = this.parentNode.firstChild; 
    if (firstChild) { 
      this.parentNode.insertBefore(this, firstChild); 
    } 
  }); 
};

function ready(error, us, maptemplate) {
  if (error) throw error;

console.log(us, maptemplate);

//Sets color scale
  var numMedian = d3.median(maptemplate, function(d) { return d.num;}); 
  var quantize = d3.scale.quantize()
    .domain([0, numMedian])
    .range(d3.range(5).map(function(i) { return "q" + i + "-9"; }));
 
  //Pair data with state id
  var dataByFIPS = {};
  maptemplate.forEach(function(d) { dataByFIPS[d.FIPS] = +d.num; });

//Pair state name with state id
  var stateByFIPS = {};
  maptemplate.forEach(function(d) { stateByFIPS[d.FIPS] = d.state; });

//Appends chart headline
  d3.select(".g-hed").text("Map headline goes here");

//Appends chart intro text
  d3.select(".g-intro").text("Map intro text goes here. Write a short sentence describing the map here.");

//Append states
  map.append("g")
    .attr("class", "states")
    .selectAll("path")
    .data(topojson.feature(us, us.objects.states).features)
    .enter().append("path")
    .attr("d", path)
    //Color states
    .attr("class", function(d) { return quantize(dataByFIPS[d.id]); })
    //Hovers
    .on("mouseover", function(d) {
      var sel = d3.select(this);
        sel.moveToFront();
      d3.select(this).transition().duration(300).style("opacity", 0.8);
      div.transition().duration(300)
      .style("opacity", 1)
      div.text(stateByFIPS[d.id] + ": " + dataByFIPS[d.id])
      .style("left", (d3.event.pageX) + "px")
      .style("top", (d3.event.pageY -30) + "px");
    })
    .on("mouseout", function() {
      var sel = d3.select(this);
        sel.moveToBack();
      d3.select(this)
      .transition().duration(300)
      .style("opacity", 1);
      div.transition().duration(300)
      .style("opacity", 0);
    });

//Appends chart source
  d3.select(".g-source-bold")
    .text("SOURCE: ")
    .attr("class", "g-source-bold");

d3.select(".g-source-reg")
    .text("Chart source info goes here")
    .attr("class", "g-source-reg");

//RESPONSIVENESS
d3.select(window).on('resize', resize);

function resize() {

var w = d3.select(".g-chart").node().clientWidth;
    console.log("resized", w);

// adjust things when the window size changes
    width = w - margin.left - margin.right;
    height = width * mapRatio;

console.log(width)
    // update projection
    var newProjection = d3.geo.albersUsa()
      .scale(width)
      .translate([width / 2, height / 2]);

//Update path
    path = d3.geo.path()
      .projection(newProjection);

// resize the map container
    map
        .style('width', width + 'px')
        .style('height', height + 'px');

// resize the map
    map.selectAll("path").attr('d', path);
}
}

</script>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js

https://cdnjs.cloudflare.com/ajax/libs/queue-async/1.0.7/queue.min.js

https://cdnjs.cloudflare.com/ajax/libs/topojson/1.6.19/topojson.min.js