How it works :
It uses the browser to detect the language.
So, if your language is Spanish, you may see something like that :
Whereas I see this :
It uses Mozilla l20n lib.
But it seems not to work at all with Chrome/Chromium.
How to translate :
Create a file [your_language].l20n
The reference file is fr.l20n : it contains all the chains to translate.
Just copy them to your file, and translate !
When it's ok, you can send them back to me by mail(openbeermap[at]gmail[dot]com) or via a github pull request.