I really tried to figure this one out by myself, but… Firefox displays exceptional unicode characters in a specific, seemingly internal font. Here’s an example, both glyphs are taken from unicode block “Miscellaneous Symbols”: ☠ (SKULL AND CROSSBONES, 9760) ☃ (SNOWMAN, 9731) Go ahead and open this page in another browser, perhaps a pre-installed Internet Explorer. This is a rendering taken from my machines: http://i48.tinypic.com/e0ipes_th.png I tried out all my fonts (some of them really, really unicode-supporting) with these glyphs and others, and none of them were an exact match. It doesn't matter what font-family is set in CSS. Firefox overrides the missing glyphs. You can’t inspect the calculated font-family when omitting it. I didn't find anything when searching, since this is not a problem like “Firefox not rendering unicode font correctly”, but the opposite. What’s the solution? What’s the name of this mystical font and where do I find it?