5.8 Summary
Although authors cannot count on a specific font being used in a
document, they can very easily specify generic font families to be
used. This particular behavior is very well supported, since any user
agent that didn't let authors (or even readers)
assign fonts would quickly find itself out of favor.
As for the other areas of font manipulation, support varies. Changing
the size of fonts usually works well, but 20th-century
implementations ranged from frustratingly simplistic to very nearly
correct in this area. The frustrating part for authors is usually not
the way in which font sizing is supported, but instead in how a unit
they want to use (points) can yield very different results in
different media, or even different operating systems and user agents.
The dangers of using points are many, and using length units for web
design is generally not a good idea. Percentages, em units, and ex
units are usually best for changing font sizes, since these scale
very well in all common display environments.
The other frustration is likely to be the continued lack of a
mechanism to specify fonts for downloading and use in a document.
This means that authors are still dependent on the fonts a user has
available, and that they cannot predict what appearance that text
will take.
Speaking of styling text, there are ways to do so that
don't involve fonts, which the next chapter will
address.
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