How to insert vertical bar into diagram

In Calc I have a diagram with dates on the x axis and some values on the y axis. As the diagram covers both past and future dates I would like to insert a vertical bar as a marker for the current date.

Any hints?

May be adding one serie, only with NOW() and the hight value of the other data.
Set to not view the empty cells.

That’s what I tried already. However, the diagram I am using has stacked areas, so the marker ends up being stacked on top of the other areas or below pushing them up.

Can you upload the file to take a look?