I have a point layer in QGIS 2.18.14. I have colored the points based on a category, using the YlOrRd color ramp. Now I am trying to change the outline of each point marker to be slightly darker than the fill color. I would do it by hand, but there are dozens of them. Is there a way to do this automatically?
I have tried applying a data-defined override to the outline of the simple marker using the expression "darker(@symbol_color, 200)" as presented in solutions to these questions:
but it does not result in any change. In the expression window, the output preview shows that it's working, but the actual color of the outline just never changes. I tested the same method on a polygon layer (because both previous questions were talking about polygons, not points), and still got nothing. Any idea how I might do this better, or why the data defined override isn't working?