How do I set the font for output in my stylesheet?

Question

I'd like to change the font that Mathematica uses for output by setting the font of the corresponding style in my stylesheet; bit simply overriding the default Output style with

Cell[StyleData["Output"],FontFamily->"Open Sans",FontSize->12]

seems to have no effect.

Is there a way to do this that I'm missing? Is the style used for output something different?

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Note that this is not a duplicate of "Set default font for Output", despite the title.

Answer 1

After a bit of style sheet spelunking I believe I have a solution. It is far from well tested at this point but I'm encouraged.

One reads in Core.nb under the FormatType Styles section:

The cells below define styles that are mixed in with the styles of most cells. If a cell's FormatType matches the name of one of the styles defined below, then that style is applied between the cell's style and its own options. This is particularly true of Input and Output.

From this it becomes clear why the styles one creates for Input and Output are not respected. That leads me to my proposed method. The template for the private style sheet is as follows:

The code for the top cell, placed above the base style sheet cell, is:

Cell[StyleData["StandardForm"],
  FontFamily -> Inherited
]

This changes the way that the "Input" and "Output" styles work. Now you create font style cells for both, e.g.:

Cell[StyleData["Input"],
 FontFamily -> "Courier"
]

Cell[StyleData["Output"],
 FontFamily -> "Trajan Pro"
]

And prestidigitonium!

Answer 2

Not sure if there is a straight forward way but here is one way that works.

Edit the private styles of your notebook as per these grabs:

And now your output is Comic Sans :)

You can also:

SetOptions[EvaluationNotebook[], 
 CommonDefaultFormatTypes -> {"Output" -> OutputForm}]

but you still need to make your changes to the OutputForm style.