I have recreated the issue within this CodePen:
https://codepen.io/GeorgeBT97/pen/BxKdEW
As you can see, if you resize the Gridstack tile, the Highchart does not resize with it despite being set to 100% of the height and width of its parent div.
I have seen this thread:
https://github.com/gridstack/gridstack.js/issues/792
Which says using this approach should solve the issue:
hChart.setSize(container.width, container.height, false);
However, I don't know how or where to implement this to fix the issue. If anybody could explain it would be greatly appreciated. On a side note, despite the fact that Highchart container by default is set to 100% height and width of its parent div, you can clearly see in the CodePen that it is not the full height of the div - Can anyone explain why this is?
Many thanks, G