Highcharts pie rendering in conflict with legend

I have an example of a Highcharts pie with a top positioned legend.

    legend: {
        layout: 'horizontal',
        verticalAlign: 'top'
    }

http://ift.tt/1FKAJh1

There is an addSeries button in the demo which adds an inner pie chart. Because this adds more rows to the legend, the pie rendered is pushed down resulting in an incorrect behaviour.

Does anyone know how to fix this? The legend position must remain the same.