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Re: CSS Accessibility Analyzer

From: Roberto Scano - IWA/HWG <rscano@iwa-italy.org>
Date: Mon, 16 Feb 2004 10:34:52 +0100
Message-ID: <00c201c3f470$26de8e60$0300a8c0@iwars>
To: "Jens Meiert" <jens.meiert@erde3.com>
Cc: <w3c-wai-gl@w3.org>


----- Original Message ----- 
From: "Jens Meiert" <jens.meiert@erde3.com>
To: "Roberto Scano - IWA/HWG" <rscano@iwa-italy.org>
Cc: <w3c-wai-gl@w3.org>
Sent: Monday, February 16, 2004 10:05 AM
Subject: Re: CSS Accessibility Analyzer


Some remarks:

Absolute units -- I don't think absolutely defined values are harmful
per
se. Does a fixed margin or padding decrease accessibility? I don't think
so,
and I propose to soften the criteria used there (it should be easy to
define
e.g. 'font-size' exceptions).

Roberto:
CSS Techniques: http://www.w3.org/TR/WCAG10-CSS-TECHS/#units

* Use the "em" unit to set font sizes.
* Use relative length units and percentages. CSS allows you to use
relative units even in absolute positioning. Thus, you may position an
image to be offset by "3em" from the top of its containing element. This
is a fixed distance, but is relative to the current font size, so it
scales nicely.
* Only use absolute length units when the physical characteristics of
the output medium are known, such as bitmap images.



Jens:
Relative units -- Why does the validator extend declarations like
'font-style: normal;' or 'font-weight: 400' with the sentence 'Relative
unit of
measurement'?

Roberto:
I think it's a bug :)



Jens:
Foreground and background colors -- Is it necessary to show a warning
each
time only one of both properties is set? I a) remember the W3C CSS
validator
which showed similar warnings, but now passes on them (CMIIW), and b)
often
see developers who define (semi-) global background-colors and
area/element
specific foreground colors.

Roberto:
Yes... a warning is needed because the developer must check the colour
of the parent. It is explained in the "limitations": "

"If a foreground colour is specified without a background or vice versa,
it's not possible to determine the contrast from the CSS alone, as it
would depend on how it was applied to the HTML document tree. A similar
situation arises if transparent is used as a property value. In these
situations, the contrast is reported as a warning, as it requires
looking at to determine if the parent node provides sufficient
contrast."


Jens:
Last but not least, the icon assignment ain't useful and usable. It
might be
better to show each icon before the CSS selector it belongs to, or
(better)
before its information text.

Roberto:
Yes true... we go to fix it ;-)
Received on Monday, 16 February 2004 04:35:18 UTC

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