Golden Krishna (no relation):

I recently spent an hour chatting with Firefox developers trying to convince them that their browser should properly display the thin-space character.

That doesn’t seem to be going well. (See test suite.)

The thin space, used by typesetters long before computers, can enhance the readability between words and typographic elements like ampersands or em dashes, or it can be used to improve spacing between words in oddly-fitting lines of justified text.

Actually, you use it to separate consecutive quotation marks (’ ”) or locutions like “Poster Nº 1” and “15° C.” As a matter of principle, I have given up approximating such usages with nonbreaking space and have begun using the real thing (along with em spaces).

When given the HTML entity for a thin space (  [or just  , or just type the damned character]), Firefox 3.0 for Mac not only displays the thin space incorrectly, but also uses a visually worse and unexpected wider space…. At the end of our conversation, the developers conceded that my version of Firefox failed to accurately display the thin space, but maintained that this particular age-old typographic detail, well, didn’t matter because they couldn’t wrap their minds around what it might be used for.

Once again I see that nobody produces better copy for the Web than I do. It isn’t solely your fault: Your tools may fail you even if you aren’t using Windows.