following a suggestion in another thread, I tried turning a regular line_chart into an area chart.
On the "design" tab, the last two variations are area_charts, and looking at it made me realize they even do stack up - the "area" made by the second line is stacked on the one made by the first line.
<=> Now the lines aren't smooth anymore (I had set them to "smoothened" on the "formulas" tab). Can I somehow do that again?`
Thanks a lot!