W3C home > Mailing lists > Public > www-style@w3.org > January 2014

Re: [css-fonts] Specify that the default "medium" font-size should by 16px?

From: Peter Moulder <pjrm@mail.internode.on.net>
Date: Mon, 20 Jan 2014 20:04:09 +1100
To: www-style@w3.org
Message-ID: <20140120090409.GB4498@mail.internode.on.net>
On Fri, Jan 17, 2014 at 08:51:28AM -0800, Tab Atkins Jr. wrote:

> Please reread <http://dev.w3.org/csswg/css-values/#absolute-lengths>.
> The 'px' unit is an absolute unit, defined to have a 96:1 ratio with
> the 'in' unit (and thus a 4:3 ratio with the 'pt' unit).  It has
> nothing to do with device pixels, which is what is measured by DPI.

That last sentence is going too far: as has already been pointed out in this
thread, it does indeed have something to do with device pixels.  From the cited
document:

  # For such devices [i.e. of low resolution, or with an unusual viewing
  # distance] it is recommended that the pixel unit refer to the whole number
  # of device pixels that best approximates the reference pixel.

Thus, while the CSS <length> 16px is equal to the CSS <length> 12pt, it is not
necessarily equal to 12 pt, and (more importantly) is not necessarily the best
available approximation of either 16 reference px or of a comfortable reading
size.

That said, a note along the lines that John Daggett suggested sounds reasonable.

pjrm.
Received on Monday, 20 January 2014 09:04:30 UTC

This archive was generated by hypermail 2.4.0 : Friday, 25 March 2022 10:08:38 UTC