svg.interactive-plot {
  width: 100%;
  max-width: 600px;
  height: 320px;
  border: 1px solid #ccc;
}

svg.interactive-plot .axis path,
svg.interactive-plot .axis line {
  stroke: #000;
}

svg.interactive-plot .hover-line {
  stroke: red;
  stroke-dasharray: 4;
  stroke-width: 3;
}