When the scrollbar is slightly off towards the bottom of the page the tooltip is practically unreadable because it's going off screen on the top. I get the same problem with both GanttChart and Highchart itself. Could you please provide me some information about how I can prevent this from happening?
Fiddles:
1. Gannt chart (I'm sorry for taking someone's example but it suits me perfectly)
https://jsfiddle.net/ymaonfpu/
2. Highchart
http://jsfiddle.net/k7anc0fb/11/