OT: CSS details

[Jay R. Ashworth]

On Fri, Aug 22, 2008 at 02:45:24PM -0400, Kenneth Brody wrote:
> Quoting Jay R. Ashworth (Fri, 22 Aug 2008 13:33:51 -0400):
> >On Fri, Aug 22, 2008 at 10:15:27AM -0700, Tyler wrote:
> >>Regarding px: *I* didn't class it that way - the CSS standard does.  A
> >>pixel is considered relative in size to the *screen resolution*, not
> >>other page elements.  So a pixel on a screen with a resolution of
> >>640x480 will be larger than a screen with a res of 1024x768.
> >
> >Citation, please?
> >
> >A pixel is in fact, *physically larger*, if you run the same physical
> >screen size at those 2 different resolutions, but I don't think that's
> >what you mean...
> 
> http://www.w3.org/TR/REC-CSS1-961217#length-units
> 
>  These relative units are supported:
> 
>   H1 { margin: 0.5em }      /* ems, the height of the element's font */
>   H1 { margin: 1ex }        /* x-height, ~ the height of the letter 'x' */
>   P  { font-size: 12px }    /* pixels, relative to canvas */
>   ...
>   Pixel units, as used in the last rule, are relative to the resolution of
>   the canvas, i.e. most often a computer display. If the pixel density of
>   the output device is very different from that of a typical computer
>   display, the UA should rescale pixel values. The suggested reference
>   pixel is the visual angle of one pixel on a device with a pixel density
>   of 90dpi and a distance from the reader of an arm's length. For a nominal
>   arm's length of 28 inches, the visual angle is about 0.0227 degrees.

Be damned.

So "px" actually means "90th of an inch".  Does "pt" always mean ...
no, I'll just go look.

Thanks for the link, Ken.

Cheers,
-- jra
-- 
Jay R. Ashworth                   Baylink                      jra at baylink.com
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