itemBackgroundColorOnHover: String

Sets the background color of particular option (zoom/pan, reset, export-menu & export-options) within toolbar on mouse hover. Values of itemBackgroundColorOnHover can be specified in “HTML Color Name”, “hex code” or “rgba values”.

var chart = new CanvasJS.Chart("container",
{
 .
 .
 toolbar: {
     itemBackgroundColorOnHover: "#eccaa0",
     .
     .
 },
 .
 . 
});
chart.render();