kai but maybe it would be not so much work for you to make the text size of the different containers in each invoice adjustable for users?
There are currently 3 different font sizes used in each invoice: heading, main text & footer (in layout 4 there are two different font sizes used in the "footer"/sidebar). So it would require at least 3 settings to adjust them individually. Since the goal of this app is to be as simple and minimalistic as possible, I am not sure if it would be worth the tradeoff, but I'll think about it more...