svg {
    font: 12px sans-serif;
    font-weight: bold;
    margin: 10px;
}

.axis,
.frame {
    shape-rendering: crispEdges;
}

.axis line {
    stroke: #ddd;
}

.axis path {
    display: none;
}

.cell text {
    font-weight: bold;
    text-transform: capitalize;
    fill: black;
}

.frame {
    fill: none;
    stroke: #aaa;
}

circle {
    fill-opacity: .5;
}

circle.hidden {
    fill: #ccc !important;
}

.extent {
    fill: #000;
    fill-opacity: .125;
    stroke: #fff;
}