When you access sgf files locally (using "file:" URL's
for example) you can explain the browser that these files (ending
with filename extension .sgf) still should be treated
as datatype:
application/x-go-sgf
You can accomplish this by adding the following line:
application/x-go-sgf sgf
to your file:
${HOME}/.mime.types
Note
Don't forget to
reload .mime.types
in case you make changes to it.