sankey tooltip calc relative to div.svg-container rather than gd

Author: monfera

src/traces/sankey/plot.js

@@ -135,7 +135,7 @@ module.exports = function plot(gd, calcData) {
 
     var linkHoverFollow = function(element, d) {
         var trace = d.link.trace;
-        var rootBBox = gd.getBoundingClientRect();
+        var rootBBox = d3.select(gd).select('.svg-container').node().getBoundingClientRect();
         var boundingBox = element.getBoundingClientRect();
         var hoverCenterX = boundingBox.left + boundingBox.width / 2;
         var hoverCenterY = boundingBox.top + boundingBox.height / 2;