This demo shows how we can use an adapter to adaptively color X-axis tooltip based on series tooltip color, which in turn is based on whether specific data item has a value lower on higher than its predecessor.
Code
xAxis.get("tooltip").get("background").adapters.add("fill", function(fill, target) { return series.get("tooltip").get("background").get("fill"); });
xAxis.get("tooltip").get("background").adapters.add("fill", function(fill, target) { return series.get("tooltip").get("background").get("fill"); });
Example
See the Pen
Automatically adjust X-axis tooltip color based on series by amCharts team (@amcharts)
on CodePen.0