Невозможно разместить всплывающую подсказку на гистограмме d3js

var width = 216;
var height = 200;
var barPadding = 18;
var barWidth = 58;
var dataSize = d3.selectAll(dataset).size();
var margin = {
  top: 10,
  right: 0,
  bottom: 58,
  left: 30
};
var width_box_sizing_border_box = width + margin.left + margin.right;
var height_box_sizing_border_box = height + margin.bottom + margin.top;




var graph;
var xScale;
var yScale;
var dataset;

var xTicks = 6;
var yTicks = 6;
var tooltipEl = function(d) {
  return (
    '<div>' + d.val + '</div>'
  )
}

dataset = [{
  desc: 'test1',
  val: 40
}, {
  desc: 'some dummy text here',
  val: 120
}];

xScale = d3.scaleBand()
  .domain(dataset.map(function(d) {
    return d.desc;
  }))
  .range([margin.left, width - margin.right]);

yScale = d3.scaleLinear()
  .range([height, 0])
  .domain([0, 350]);

graph = d3.select("#graph")
  .append("svg")
  .attr("class", "bar-chart")
  .attr("width", width_box_sizing_border_box)
  .attr("height", height_box_sizing_border_box);

// Tool Tip
const div = d3
  .select('#graph')
  .append('div')
  .attr('class', 'tooltip')
  .style('opacity', 0);

graph.append("g")
  .attr("class", "x-scale")
  .attr("transform", "translate(0," + (height + margin.top) + ")")
  .call(d3.axisBottom(xScale).ticks(xTicks))
  .selectAll(".tick text")
  .call(wrap, xScale.bandwidth());

graph.append("g")
  .attr("class", "y-scale")
  .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
  .call(d3.axisLeft(yScale).ticks(yTicks).tickPadding(10));

graph
  .append("g")
  .attr("transform", "translate(" + (xScale.bandwidth() / 2 - (barWidth - barPadding) / 2) + "," + margin.top + ")")
  .attr('class', 'graph-placeholder')
  .selectAll("rect")
  .data(dataset)
  .enter()
  .append("rect")
  .attr("class", "bar1")
  .attr("height", height)
  .attr("width", barWidth - barPadding)
  .attr('x', d => xScale(d.desc));

graph
  .append("g")
  .attr("transform", "translate(" + (xScale.bandwidth() / 2 - (barWidth - barPadding) / 2) + "," + margin.top + ")")
  .attr('class', 'graph-main')
  .selectAll("bar1")
  .data(dataset)
  .enter()
  .append("rect")
  .attr("class", "bar2")
  .attr('x', d => xScale(d.desc))
  .attr("y", function(d) {
    return yScale(d.val);
  })
  .attr("height", function(d) {
    return height - yScale(d.val);
  })
  .attr("width", barWidth - barPadding)
  .on('mouseover', d => {

    div
      .html(tooltipEl(d));

    div
      .transition()
      .duration(200)
      .style('display', 'block')
      .style('opacity', 1);
    div
      .style('left', xScale(d.desc) + 'px')
      .style('top', (height + margin.top + 8) + 'px');
  })
  .on('mouseout', () => {
    div
      .transition()
      .duration(500)
      .style('opacity', 0)
      .style('display', 'none')
  });


graph
  .append("g")
  .attr("transform", "translate(" + (xScale.bandwidth() / 2 - (barWidth - barPadding) / 2) + "," + margin.top + ")")
  .attr('class', 'bar-label')
  .selectAll("text")
  .data(dataset)
  .enter()
  .append("text")
  .text(d => d.val + '%')
  .attr("y", function(d) {
    return yScale(d.val) - 5;
  }).attr('x', function(d) {
    return xScale(d.desc) + ((barWidth - barPadding) / 2 - d3.select(this).node().getBBox().width / 2);
  });

function wrap(text, width) {
  text.each(function() {
    var text = d3.select(this),
      words = text.text().split(/\s+/).reverse(),
      word,
      line = [],
      lineNumber = 0,
      lineHeight = 1,
      y = text.attr("y"),
      dy = parseFloat(text.attr("dy")),
      tspan = text.text(null).append("tspan").attr("x", 0).attr("y", y).attr("dy", dy + "em");
    while (word = words.pop()) {
      line.push(word);
      tspan.text(line.join(" "));
      if (tspan.node().getComputedTextLength() > width) {
        line.pop();
        tspan.text(line.join(" "));
        line = [word];
        tspan = text.append("tspan").attr("x", 0).attr("y", y).attr("dy", ++lineNumber * lineHeight + dy + "em").text(word);
      }
    }
  });
}

.bar-chart {
  background-color: #ccc;
}

.bar2 {
  fill: steelblue;
}

.bar1 {
  fill: #f2f2f2;
}

text {
  font-size: 12px;
  text-anchor: middle;
}

.bar-label text {
  text-anchor: start;
}

path.domain {
  stroke-width: 0;
  display: none;
}

.tooltip {
  background: #FFFFFF;
  box-shadow: 0px 0px 12px rgba(0, 0, 0, 0.33);
  font-family: "Segoe UI";
  line-height: normal;
  padding: 15px;
  width: 400px;
  position: absolute;
  display: none;
}

.tooltip__container {
  display: flex;
}

.tooltip::before {
  content: "";
  position: absolute;
  left: 22px;
  top: -8px;
  transition: all 0.5s ease;
  border: 8px solid #fff;
  box-shadow: -5px -5px 5px rgba(0, 0, 0, 0.1);
  transform: rotate(45deg);
}

<script src = "https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>
<div class = "container">
  <div id = "graph"></div>
</div>