Since release 2019.3, it is possible to format colors for negative plot areas in a chart with a different color, using the Advanced Chart Properties feature.
Remove x-axis from diagram but preserve the labeling
Merged
It would be helpful to remove the x-axis line in diagrams but preserve the labeling of the axis because in modern report design you often do not want to show the x-axis itself.
https://api.highcharts.com/highstock/plotOptions.series.zones
Since release 2019.3, it is possible to format colors for negative plot areas in a chart with a different color, using the Advanced Chart Properties feature.