When visiting the gopherjs serve main page, Chrome seems to think the page is in Italian:

I believe this is because the page does not include proper Content-Language meta tags:
<meta http-equiv="Content-Language" content="en">
Setting the language on a directory listing feels dirty to me. What if my filenames are in Italian? Or what if they are English, but my browser is in another language? I certainly don't want that page to be translated. It's really not in any (human) language at all. I don't know if there's an official way to handle this situation, but I would at least experiment with the first two lines in that SO answer:
<meta charset="UTF-8">
<meta name="google" content="notranslate">
And see if that alone does the trick. If not, then specifying en might be better than not... but it doesn't feel "right" to me.
Agreed with @flimzy.
I just want to add that http.FileServer does not set <meta http-equiv="Content-Language" content="en">, and that's what gopherjs serve uses. So to some degree, this is a bug you should file against net/http. Of course, GopherJS could be modified to use a custom implementation instead of the one from net/http, but you get my point.
Also, I can't repro this, I'm guessing it happens to you because of one of the folder names.

That would suggest this won't affect many people.
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Agreed with @flimzy.
I just want to add that
http.FileServerdoes not set<meta http-equiv="Content-Language" content="en">, and that's whatgopherjs serveuses. So to some degree, this is a bug you should file againstnet/http. Of course, GopherJS could be modified to use a custom implementation instead of the one fromnet/http, but you get my point.Also, I can't repro this, I'm guessing it happens to you because of one of the folder names.
That would suggest this won't affect many people.