Donut size changes with no of labels in the legend

In the fiddle below, I have 3 charts generated by c3js. I want to fix the size of the chart but it can be seen that the donut size varies according to the legend.

https://jsfiddle.net/anu23/qzew784d/2/

Is there way to keep the donut size fixed regardless of the legend label length and the no of labels in the legend. I want to export these chart and want to fix the donut size. The donut size also changes in Safari and long labels in legend make the size of the donut very small. Because I'm loading the chart with dynamic data and there are multiple charts in a page, it looks bad with different sizes.