On 2009/08/10 16:22 (GMT-0700) Theresa Mesa composed: > What I find amusing about the admonition to use points is that points > are printing-industry-based, not monitor- or Web-based. There are 12 > points in a pica, or 72 points in an inch. Back in the day, one pica > was .166 of an inch; now it is 1.6 of an inch. But we don't use inches > or picas when discussing the web.
> I'm aware of the discussions about using point sizes on the web, so > I'm not opening that discussion. A pt has the same meaning in CSS, but the problem is its inaccuracy as used in a web browser. Most personal computers used for the web use an arbitrarily assumed DPI, while an accurately sized pt requires an accurate DPI be applied for a screen pt to match the physical size of a printed pt. The result of the wild variation in accuracy is that pt, like px, as a CSS sizing unit, bears little predictable relationship to the resulting physical size of the objects it is applied to, or any physical size any particular user of a page styled in CSS would find appropriate for his own use on his _personal_ computer. Consequently, on today's web, CSS styling in px should be no more or less objectionable than CSS styling in pt. > An em is another issue. On the surface, an em is a unit of measurement > that uses the width of the capital "M" in a font... > http://en.wikipedia.org/wiki/Pica_(unit_of_measure) > http://desktoppub.about.com/cs/intermediate/a/picaspoints.htm > Theresa (graphic designer - and old-time typesetter - for 38 years now) The CSS specs define em differently than you are used to for media other than the web: http://www.w3.org/TR/CSS21/syndata.html#em-width In contrast to px and pt, sizing in em results in a predictable physical size; predictable in the sense that it bears a useful relationship to a size the user finds suitable for personal use, 1em, the size of his browser's default font. If you think about it, you may find sizing in em isn't vastly different than sizing in picas. The main difference is that the visitor via his browser prefs determines the size of the em, while the pica is a fixed physical size. When a web author uses em sizing in his CSS, he's essentially creating resolution independent design. IOW, to an author sizing primarily or totally in em, resolution is a totally non-issue. Even though computer desktops are not yet resolution independent, CSS styled web pages can be. -- How much better to get wisdom than gold, to choose understanding rather than silver. Proverbs 16:16 NKJV Team OS/2 ** Reg. Linux User #211409 Felix Miata *** http://fm.no-ip.com/ ______________________________________________________________________ css-discuss [cs...@lists.css-discuss.org] http://www.css-discuss.org/mailman/listinfo/css-d List wiki/FAQ -- http://css-discuss.incutio.com/ List policies -- http://css-discuss.org/policies.html Supported by evolt.org -- http://www.evolt.org/help_support_evolt/
