Felix, you answer is very helpful and very informative, but there are places where (to me) it seems to make no sense at all. May I ask you to expand on the following, please ?
DPI is often used interchangeably with display resolution
DPI is a single number (1-dimensional) whilst display resolution is an ordered pair (2-dimensional); how can they be used interchangeably ?
DEs for desktop systems (and the software than runs on them, including web browsers) almost universally by default assume a display density of 96 DPI (or PPI), same as the CSS reference px unit.
It has never been clear to me why CSS has a reference px unit. What is the point of CSS including a unit such as "px", which should mean "one pixel", and then giving it an entirely arbitrary meaning that does not (other than by pure chance) map to one pixel at all ?
In Geckos, variations in assumed DPI have no impact on its 16px OEM default size, which physically speaking is 12pt whenever the DPI is in fact 96.
Why ? Also, has this always been the case, or did it change between the version of Gecko used until Seamonkey 2.17.1 (the last version that I regard as usable, because of the aberrant behaviour regarding font scaling that occurred post that release) and subsequent versions ?
To get bigger fonts in px from Geckos requires either settings personalization, zoom, or bigger CSS size declarations, all of which are effective in IE as well, but often obviated from necessity because IE's default automatically goes up as DE DPI goes up, e.g., default @120 DPI being 20px instead of the 16px that it is @96, or 24px when DPI is 144.
Why does Gecko not emulate this eminently sensible behaviour ?
The reason it's ostensibly a good thing is because there is positive non-zero rational relationship between a CSS size declaration in em, and to optimal as reflected by the browser default size, which does not exist for a px unit.
I don't understand the above starting at "and to optimal"; is there possibly a typo somewhere in there that is confusing me ?
as display density increases, the px unit decreases in physical size (to a point, after which it doubles, and then at another point, after which it in effect will have tripled, etc.),
What causes it to ?suddenly? double, triple, etc ? Many thanks in advance for any light that you can shed on the above. Philip Taylor ______________________________________________________________________ css-discuss [css-d@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/
