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RE: Question on F3: Failure of Success Criterion 1.1.1 due to using CSS to include images that convey important information

From: Jonathan Avila <jon.avila@ssbbartgroup.com>
Date: Tue, 22 Jul 2014 12:28:01 +0000
To: Aurélien Levy <aurelien.levy@temesis.com>, "w3c-wai-gl@w3.org" <w3c-wai-gl@w3.org>
Message-ID: <1f10c20ddfa44175ada8c70445400bf0@BY2PR03MB272.namprd03.prod.outlook.com>
Thanks Aurelien, I was considering this some more and conformance for the site as a whole came to me.  Regarding turning CSS off completely - If that were a route then the entire site would have to work without CSS to conform unless an alternative page was provided.   In theory a link that reset CSS on a page might count as an alternative page.  But I couldn't see a claim that an alternative page required the user to manually turn of CSS just for that page as an alternative.  For example, in my opinion an alternative page shouldn't require the user to change their browser CSS settings to conform - the page should offer the option to the user.  So this issue could slide into the area of alternative conforming pages even if F3 was found to require turning off only CSS images.

Jonathan

From: Aurélien Levy [mailto:aurelien.levy@temesis.com]
Sent: Tuesday, July 22, 2014 3:54 AM
To: w3c-wai-gl@w3.org
Subject: Re: Question on F3: Failure of Success Criterion 1.1.1 due to using CSS to include images that convey important information

Hi Jonathan,

I want to ask the same question ;). I agree with you, for me it's a failure with the current text especially with the condition number 3 of the test procedure who state "and is also available when the CSS image is not displayed." (for me not displayed doesn't mean with CSS turn off). The description of the test also say :

"Note: Embedding information into a background image can also cause problems for people who use alternate backgrounds in order to increase legibility and for users of high contrast mode in some operating systems. These users, would lose the information in the background image due to lack of any alternative text"

I think there is two things that may lead to think it's not a failure :
- there is a sufficient technique allowing to use hidden text with css http://www.w3.org/TR/WCAG20-TECHS/C7.html (so same technique but in one case is a failure and in an other case it's not)
- for me an association with the guideline 1.3 is missing because using user css or high contrast mode is clearly a case where  content is presented in different ways and it must be without losing information or structure.

Aurélien

Step 3 of the check for F3 states "If an image does convey important information, the information is provided to assistive technologies and is also available when the CSS image is not displayed."

I'm looking to gather opinions one whether it is acceptable to pass this check by completely turning off CSS.

The common scenario is that pages use background images to convey meaning and then provide off-screen position CSS text for screen readers or for viewing when CSS is turned off.  This forces users with low vision who use high contrast or ignore colors to completely turn off CSS for the page.  Requiring the user to turn of CSS to simply have access to a meaningful image that the developer should not have made a presentation layer image is an issue for me.  Knowledgeable people in our field have stated on their blogs that they don't consider this an accessibility issue and only consider it a usability issue.

Thus, my question then comes down to this failure.   The check does not say to turn off CSS but only that the information be available with CSS images are not displayed - thus, I feel it is reasonable to require a visual alternative when CSS images are disabled but CSS is still on.  Is there any consensus on this?   Thank you for considering this item.

Jonathan




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Aurélien Levy

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Temesis
Received on Tuesday, 22 July 2014 12:28:37 UTC

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