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Re: Specifying foreground and background colors

From: Wendy A Chisholm <wendy@w3.org>
Date: Thu, 08 Jun 2000 11:31:01 -0400
Message-Id: <4.2.0.58.20000608112141.04ca19d0@localhost>
To: w3c-wai-gl@w3.org
I have two questions in relation to this issue:
1. will user agents automatically make adjustments for background or 
foreground color if the author specifies a good combination but the user 
only specifies one or the other (foreground or background but not 
both)?  It is my experience that user agents do not.

2. I intend to include this in the techniques document, but would like a 
rationale.  It seems that the rationale is good design rather than an 
accessibility issue since the answer to the first question seems to be "no."

If there is no disagreement, I propose editing section 5 (Colors) of the 
CSS techniques module to read:
<blockquote>
Use these CSS properties to specify colors:
'color', for foreground text color.
'background-color', for background colors.
'border-color', 'outline-color' for border colors.
For link colors, refer to the :link, :visited, and :active pseudo-classes.

Note that when a background color is specified, specify a high-contrast 
foreground color and vice-versa.

Ensure that information is not conveyed through color alone. For example, 
when asking for input from users, do not write "Please select an item from 
those listed in green." Instead, ensure that information is available 
through other style effects (e.g., a font effect) and through context 
(e.g,. comprehensive text links).
For instance, in this document, examples are styled by default (through 
style sheets) as follows:
They are surrounded by a border.
They use a different background color and also specify a high-contrast 
foreground color.
They begin with the word "Example" (or "Deprecated Example".
They also end with the phrase "End example", but that phrase is hidden by 
default with 'display: none'. For user agents that don't support style 
sheets or when style sheets are turned off, this text helps delineate the 
end of an example for readers who may not be able to see the border around 
the example.
</blockquote>
--wendy

At 12:59 AM 6/7/00 , Wendy A Chisholm wrote:
> From the issues list:
>
><blockquote>
>Issue raised by: Philip Newton - 7 May 1999
>Issue:
>If the author specifies a background color, they should also specify the 
>foreground color (and vice versa), otherwise if the user has selected a 
>particular foreground color that does not contrast well with the author's 
>background color, the page will be unreadable.
>
>Proposed Resolution
>While the user should be able to adjust preferences on the user agent, it 
>is good design. Therefore, it seems to make sense to discuss in techniques doc.
></blockquote>
>
>Even if the author selects both a background and text color, if the user 
>selects a foreground color that does not contrast well with the author's 
>background color then what can you do?  If the user only selects one color 
>but the author has selected both foreground and background, the user agent 
>will not automatically use colors that contrast well, will it?
>
>I agree this is good practice but I am not sure that this increases 
>accessibility.
>
>Thoughts?  Do people have experiences that support the proposal?  Does 
>someone have a good test page for this?
>--wendy
>--
>wendy a chisholm
>world wide web consortium
>web accessibility initiative
>madison, wi usa
>tel: +1 608 663 6346
>/--

--
wendy a chisholm
world wide web consortium
web accessibility initiative
madison, wi usa
tel: +1 608 663 6346
/--
Received on Thursday, 8 June 2000 11:25:53 GMT

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