superset/panoramix/static/widgets/viz_bignumber.css

.viz_bignumber g.axis text {
  font-size: 10px;
  font-weight: normal;
  color: gray;
  fill: gray;
  text-anchor: middle;
  alignment-baseline: middle;
  font-weight: none;
}

.viz_bignumber text.big {
  stroke: black;
  text-anchor: middle;
  fill: black;
}

.viz_bignumber g.tick line {
  stroke-width: 1px;
  stroke: grey;
}

.viz_bignumber .domain {
  fill: none;
  stroke: black;
  stroke-width: 1;
}