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Re: Font sizes

From: Graham Oliver <graham_oliver@yahoo.com>
Date: Mon, 27 Aug 2001 22:08:12 +0100 (BST)
Message-ID: <20010827210812.56930.qmail@web10004.mail.yahoo.com>
To: Paul@ten-20.com, w3c-wai-ig@w3.org
Hi Paul

'Partially sighted readers prefer non-serif fonts'
p 59 'Site Seeing' by Eric Velleman and Henk
both of the Bartimeus Educational Institute.

Also see this page
which covers font research on people without a visual
impairment (as far as I can tell).
Note the dangers they highlight of using 10 point (or
less) serif fonts.

Yet, as seen in Figure 4, other than the 12-point TNR
font, the TNR fonts were the least preferred. 
One reason for this could be that  at smaller font
sizes on computer screens, the serifs stop acting as
distinguishers and start becoming visual 'noise.'
Moreover, small anti-aliased fonts may create even
more visual noise because of the smoothing effects of
the anti-aliased font. This would explain the very
poor performance of the 10-point anti-aliased TNR

Here is something I put together on font size and
enlargement issues which are vital for people with a
visual impairment

<Font Size Enlargement Info>
Font size can be specified using the FONT element in
HTML or using the font-size property in CSS.

The rationale for not using the FONT element is that
it increases maintenance costs, has been deprecated in
HTML 4.01, doesn't allow the user to control font size
using personal style sheets and is less flexible than
the font-size property in CSS.

The following considers the strategy to follow to
allow enlargement of text, given that CSS are used to
implement font size.
There are 4 possibilities to specify font size:

-Absolute Size
The keywords used to express font size range from
'xx-small' to 'xx-large'

-Relative Size
The keywords used to express font size are 'smaller'
and 'larger'

Height can be expressed in a number of units,
including points (pt), pixels (px), ems (em) and

A percentage font size as a percentage of the parent
font size.

Although both Absolute and Relative Size fonts do
enlarge, they are implemented differently across
browsers. Their use would serve to overly restrict
design decisions and usability.
The only Height unit that allows enlargement in
Internet Explorer is the 'em'.
The Percentage unit also allows enlargement.

Thus, the use of either the 'em' or the '%' unit is
recommended to allow enlargement of text.
</Font Size Enlargement Info>

Graham Oliver

'Making on-line information accessible'
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Received on Monday, 27 August 2001 17:08:15 UTC

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