For example, if the container is 200px x 100px, the chart will be 100px x 100px.
And if the container is 150px x 300px, the chart will be 150px x 150px.

If there is a need to make a square chart in a responsive container with width defined and automatic height. For now Highchart detects the width and make the height of the chart the same as the width. This can result in the chart overflowing the container when the height is smaller than the width.

Highcharts could automatically detect the lesser (width or height) and make the chart dimensions be the least of the two => and so fit the container.