Question

Consider an HTML page which is encoded as UTF-8, and a bizarre unicode character appears in it – form a rare language or some other Unicode idiosyncrasy.

Is there a standard behavior for such scenario? Will the browser try to find an appropriate font? Can the browser behavior be configured using HTML parameters?

Answer 1

The CSS 2.1 font matching algorithm means that a browser shall select, for each character, a glyph from the fonts suggested in the applicable font-family declarations and, failing that, use a browser-dependent default font. If even it does not contain the character, then “the UA [= browser] may use other means to determine a suitable font for that character. The UA should map each character for which it has no suitable font to a visible symbol chosen by the UA, preferably a ‘missing character’ glyph from one of the font faces available to the UA.”

So it is pretty well defined, but with browser dependencies. The algorithm allows a browser to display a missing character symbol even if some of the fonts in the system contains a glyph for it. Modern browsers usually don’t do that, but IE isn’t particularly modern in this respect either. Moreover, there are quirks and oddities in browsers, partly because they sometimes fail to get proper information about a font from the font itself.

You can’t configure the basic behavior, but you can play by its rules. The thing that works best is the use of author-supplied font families. If you have an odd character, you should try and determine a set of fonts that contain it and write a suitable CSS rule. However, for very rare characters the options are really: 1) the use of a downloadable font for it, 2) the use of an image. More info: http://www.cs.tut.fi/~jkorpela/html/characters.html