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Re: CSS-P, layers, links and accessibility

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From: Leo Smith
Date: Jul 25, 2001 9:32AM

Tom...thanks so much for your input.
I have actually used solely absolute positioning before to create
some websites (before I was designing for accessiblity), and have
had no other problems with NS4 - I use NS 4.03 as my test. This
tabbing issue is the only problem that I have encountered so far.
NS 4.03 seems to render layout perfectly using the position, left,
top, z-index, width, height and visibilty attributes. I also much
prefer to use CSS-P as it is a lot easier to manage and adjust than
tables for complex layouts, and I have found it to be more reliable
than complex tables for consistent layout across browsers
(especially with NS4, which has a number of nuances with table
layouts).
However, I would like to find a solution to this tabbing issue if one
exists....
Thanks Again..
Leo.

On 25 Jul 2001, at 10:07, Tom Dahm wrote:
Leo,

I'd advise you to stay away from CSS positioning. Netscape 4
doesn't support this reliably enough to make it a safe technology,
and NN 4 still makes up about 15% of the browser market. 

In general I'd be cautious about full implementation of the WAI
guidelines, since they're based on the assumption that all browsers
fully support the latest W3C standards. 

Even though CSS isn't exactly a new standard, and the latest
versions of NN and IE support it well, the presence of old
browsers means you can't hang your hat on it yet. There are a lot
of other accessibilty tags in the HTML standards that aren't
widely supported yet (LABEL is a good example). 

That's the main reason for the difference between the 508
requirements and the WAI guidelines. The WAI rules are based
on the browser market as it should be; the 508 guidelines are
based on the market as it really exists today. 

Hope this helps.

Tom Dahm
NetMechanic, Inc.
"Power Tools for Your Web Site"
http://www.netmechanic.com
At 08:55 AM 7/25/01 -0400, you wrote: 
Hi everyone, 

I had a couple of questions regarding absolute positioning and accessibility th
was hoping someone could clear up for me. 
I am hoping to implement CSS-P (absolute positioning or what Dreamweaver calls
layers) as much as possible in the site thI
am presently redesigning, as I would very
much like to get away from using tables for complex layouts. 

I have read a good deal of literature about web accessibility and the fact that CSS shd
be used as much as possible for presentatio and layout. The W3C techniques section for checkpoints 3.3 and 5.3 states that: Layout positioning, layering, and alignment
should be done through style sheets
(notably by using CSS floats and
absolute positioning):'float', 'position', 'top', 'right', 'bottom', 'left'. With thes properties, the user can control the visual position of almost any element in a
manner independent of where the
element appears in the document.
Authors should always design
documents that make sense without style
sheets (i.e., the document should be
written in a "logical" order) and then appl style sheets to achieve visual effects. 


However, I have found that when using layers, that
links contained within them are not accessible via
the tab key in Netscape 4x or 6, whether I use the
<div> or <span> tag to code the layer. 

For example: 

<span id="Layer1" style="position:absolute;
visibility:visible; z- index:1; left:50px; top:150px;
width:100px"><a
href="somewhere.htm">link</a></span> 

or 

<div id="Layer1" style="position:absolute;
visibility:visible; z- index:1; left:50px; top:150px;
width:100px"><a
href="somewhere.htm">link</a></div> 

neither of these allow links contained within them
to be tabbed to when viewed in these browsers. 

I have not read anything in the 508 or W3C
guidelines that specifically says all links on a page
should be accessible through the tab key, other
than W3C Priority 3 specification 9.4 which states
"create a logical tab order through links, form
controls and objects". 

Does the fact that Netscape 4x or 6 browsers do
not allow access to links within a layer through the
tab key mean that absolute positioning should be
avoided? 


Also, both the 508 and the W3C guidelines state
that a document should be readable when style
sheets are turned off. 
Am I correct in assuming that inline styles do not
come under "style sheet" in this directive? 

That is, an inline style such as: 
<span style="background-color:#ffffcc">hello
everybody</span> 

or like the layers above: 
<div style="position:absolute; left:10px; top:50px;
width:100px">The quick brown fox jumped over the
log</div> 

would not be included under this style sheet
independence directive. 


Thanks so much for your time and valuable input. 

Best, 

Leo. 

Leo Smith USM Office of Publications and Marketing 207-780-4774 


Leo Smith
USM Office of Publications and Marketing
207-780-4774