The default config.toml has this config about the viewer:

viewer = [
    "firefox",
    "%p",
]

The problem with this config is that it doesn't do the job becouse firefox, like any other browser (atleast on Windows OS) wants this syntax:

file:///%p

So if the path is C:\Temp\test.md the right argument to pass to the browser is
file:///C:\Temp\test.md or file:///C:/Temp/test.md
(works both ways)

How to achieve this?