How can I set an equirectangular projection like the one in this example http://bl.ocks.org/mbostock/3757119 as a background for only the chart above the X-axis? Alternatively, is it possible to use an image of a map as a CSS background instead?
.grid .tick {
stroke: lightgrey;
opacity: 0.7;
}
.grid path {
stroke-width: 0;
}
.chart {}
.main text {
font: 10px sans-serif;
}
.axis line, .axis path {
shape-rendering: crispEdges;
stroke: black;
fill: none;
}
circle {
fill: steelblue;
}