Re: Caution about Style Sheets

At 9:05 PM -0600 1/16/01, Jim Thatcher wrote:
>As you all know, the Section 508 standards include a slightly reworded
>WCAG Checkpoint 6.1.
>1194.22 (d) Documents shall be organized so they are readable without
>requiring an associated style sheet.
>What can go wrong with the use of style sheets that require this provision?
>Thanks.

Hi, Jim, here's the main ways in which CSS can cause accessibility
problems:

(1) Using CSS instead of structural markup

     For example, using this instead of an H1:

     .headline { font-size: x-large; font-weight: bold; }

     <p class="heading">This is the headline</p>

     This kind of error will often be introduced by CSS-aware
     WYSIWYG editors.

(2) Combining CSS and presentational markup incorrectly

     If you're mixing and matching CSS and presentational markup,
     you need to make sure you're not creating something such as
     black text on black backgrounds when CSS is turned off.

(3) Use of CSS-P (positioning CSS) which does not linearize well

     CSS-P (part of CSS level 2) is actually worse than tables
     when it comes to linearization problems; the ability of CSS
     to be drawn from ANYWHERE and to overlay other elements
     means that indiscriminate use of CSS-P can create documents
     which are unreadable.  As an example, my wife once received
     an "ad" for inclusion on a client's web site, which was
     created using CSS-P extensively.  Each individual visual
     component of the ad was a different CSS class, placed using
     CSS-P, and the "source" was completely out of order.

     This kind of error is almost never human introduced, and is
     the result of over-eager authoring tools.

(4) Content generation in CSS 2

     CSS level 2 allows the creation of content or markup within
     the stylesheet itself.  If this is anything other than
     purely decorative use, then you risk losing content when
     stylesheets are not used.

(5) Other WCAG violations

     Obviously there's the chance of additional CSS errors, such
     as using text effects (color) alone to indicate information
     ("all books in blue are in stock!") etc, which are covered
     by other parts of the accessibility guidelines.

Hope this helps,

--Kynn
-- 
Kynn Bartlett <kynn@idyllmtn.com>
http://www.kynn.com/

Received on Wednesday, 17 January 2001 11:17:58 UTC