Keep colours of area lines distinct when stacking them
I notice that area lines are semitransparent, so that a blue and red line with almost the same value (say 3 and 3.2) will have a purple area from 3.0 and below. I find this is fine.
But when I stack them, I want to be able to see blue from 0 to 3.0 and red from 3.0 to 6.2. At the moment, the colours still blend, so that whichever graph is on top of the stack (listed 2nd as a series) affects the colours of the area lines below it.
If you look at a stacked bars, the colours are independent for each series, with no overlap.