HTML and CSS Reference
In-Depth Information
interested authors should refer to appropriate documentation for the
Panose-1 system for more information.
The
stemv
and
stemh
descriptors define the thickness, in ems, of the ver-
tical and horizontal strokes of the font. Similarly, the
cap-height
and
x-
height
descriptors define the height of the upper- and lowercase glyphs
in the font. Finally, the
ascent
and
descent
descriptors define the font's
maximum height and depth. If you use any of these descriptors, you
must also specify the
units-per-em
descriptor.
The
slope
descriptor defines the slope of the vertical stroke of the font.
This is important for matching italic and oblique versions of a font.
The
baseline, centerline, mathline
, and
topline
descriptors define the
conventional baseline, center baseline, mathematical baseline, and top
baseline of the font. All accept a numeric value expressed in ems. All
require that you specify the
units-per-em
descriptor, too.
The
bbox
descriptor accepts exactly two coordinate (X, Y) pairs, specify-
ing the lower-left and upper-right corners of the font's bounding box.
The
bbox
descriptor is important if the browser chooses to synthesize a
font based on this font. By specifying the size of the bounding box, you
ensure that the synthesized font occupies the same space as the desired
one.
The
widths
descriptor accepts a comma-separated list of Unicode
ranges, followed by space-separated values which define the widths of
the characters in the indicated range. If you supply one value for a
range, all the characters in that range have the same width. Multiple
values are assigned to successive characters in a range. Like the
bbox
descriptor, the
widths
descriptor is used to ensure good fidelity between
a synthesized font and its requested counterpart.
Finally, the optional
definitions-src
descriptor provides the URL of a
file that contains all of the descriptors for a font. This is handy if you
need to define a font in great detail. Instead of including the lengthy
descriptors in each document or stylesheet that uses the font, you