d3/examples/box/box.css

.box .whisker, .box .median { stroke: #000; stroke-width: 1.5px; }
.box .box { stroke: #000; stroke-width: 1.5px; fill: #fff; }
.box .center { stroke: #000; stroke-width: 1px; stroke-dasharray: 3 3; }
.box .outlier { stroke: #666; stroke-width: .5px; fill: none; }