<script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>

<script src="my_chart.js"></script>

<style>
.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

.dot {
  stroke: #000;
}
</style>