[Kwant] Figsize when ax is enabled in kwant.plot

Dear All, I am trying to plot the density on top of the plot of the current. I use for that "ax" to combine the two plots. I kind of noticed that the two plots do not have the same size (although the system is the same!) I know that when "ax" is not None, "figsize" is disabled. Is there a way to fix the size of the two plots to be the same such that they can be combined? Regards, Adel