d3 linear gradient area chart: stock market close simulation (update to d3 tips and tricks)

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

body {
  font-family: Futura;
  font-size: 10px;
}

div {
  display: inline-block;

}

h1 {
  font-family: futura;
  font-size: 10px;
}

.axis {
  stroke-dasharray: 2, 2;
  stroke-linecap: "round";
  shape-rendering: crispEdges;
}

.area {
  fill: url(#area-gradient);
  stroke-width: 0px;
}

.axis line {
	stroke: #ccc;
	stroke-dasharray: 1px 1px;
}

text {
  font-family: Futura;
}

</style>
<body>

var margin = {top: 20, right: 20, bottom: 30, left: 50},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var parseTime = d3.timeParse("%d-%b-%y");

var x = d3.scaleTime().range([0, width]);
var y = d3.scaleLinear().range([height, 0]);

var	area = d3.area()
    .x(function(d) { return x(d.date); })
    .y0(height)
    .y1(function(d) { return y(d.close); });

var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform",
          "translate(" + margin.left + "," + margin.top + ")");

d3.csv("data.csv", function(error, data) {
  if (error) throw error;

data.forEach(function(d) {
      d.date = parseTime(d.date);
      d.close = +d.close;
  });

x.domain(d3.extent(data, function(d) { return d.date; }));
  y.domain([0, d3.max(data, function(d) { return d.close; })]);

var colours = ["#00ffb3","#00fff3","#00cbff","#008cff","#004cff","#000cff"];

svg.append("linearGradient")
    .attr("id", "area-gradient")
    .attr("gradientUnits", "userSpaceOnUse")
    .attr("spreadMethod", "pad")
    .style("mix-blend-mode","color-dodge")
    .attr("x1", 0).attr("y1", y(0))
    .attr("x2", 0).attr("y2", y(1000))
  .selectAll("stop")
    .data(colours)
  .enter().append("stop")
    .attr("offset", function(d,i) { return i/(colours.length-1); })
    .attr("stop-color", function(d) { return d; });

svg.append("path")
      .data([data])
      .attr("class", "area")
      .attr("d", area);

svg.append("g")
      .attr("transform", "translate(0," + height + ")")
      .call(d3.axisBottom(x));

svg.append("g")
      .call(d3.axisLeft(y));

});

</script>
</body>

https://d3js.org/d3.v4.min.js