Changing color of box background or box frame

[Michał Kruszewski]

Hello,

I often write documents including short code snippets or shell commands.
I usually put such snippets into a box using .B1 and .B2.
However, those code snippets are intended to be run on different targets, for 
example, Raspberry Pi and the host machine.

I would like to be able to somehow distinguish where to execute the code 
without requiring my users to read the text.
A good solution is to simply change the color of the background of the box or 
change the color of the box frame.

I had a few tries with the .gcolor, but I always ended up changing the color of 
both the frame and the text inside the frame or changing the color of nothing.

Does anyone know how to easily change the color of the background in the box or 
the color of the box frame?

Best regards,
Michał Kruszewski

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