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RE: Open Issue #20 - Absolute Units In Style Sheet

From: Charles McCathieNevile <charles@w3.org>
Date: Sun, 4 Feb 2001 05:50:55 -0500 (EST)
To: Michael Cooper <mcooper@cast.org>
cc: WAI ER IG List <w3c-wai-er-ig@w3.org>
Message-ID: <Pine.LNX.4.30.0102040549360.5155-100000@tux.w3.org>
There is a thing called constraint-based CSS. It was done to solve problems
like "I want all fonts to be at least 33pt", and it was implemented - it is
essentially a few extensions to CSS I think. We could look at that, or we
could ask PF to push it again...

Charles McCN

On Fri, 2 Feb 2001, Michael Cooper wrote:

  I think it's very important not to allow absolute sizes for fonts in style
  sheets. Although Netscape 6 and Opera 4 will resize text even when there's
  an absolutely defined size, all other browsers that I know of won't and you
  get frozen text. The ability to override the stylesheet doesn't help since
  it's impossible to predict in advance what elements and classes would need
  to be overridden.

  My approach to designing style sheets is to assume the browser's base font
  size is 12 point. I base all sizes off of that as either a percentage or an
  em/en. This is both resizable and, if the browser's base size is different,
  everything will still be correct with respect to that. I wish it were
  possible in CSS to define the preferred base size you're working with (as a
  single absolute size that could easily be overridden), but it isn't, so
  we're stuck relying on the browser's.


  -----Original Message-----
  From: w3c-wai-er-ig-request@w3.org
  [mailto:w3c-wai-er-ig-request@w3.org]On Behalf Of Chris Ridpath
  Sent: Friday, February 02, 2001 9:49 AM
  To: WAI ER IG List
  Subject: Open Issue #20 - Absolute Units In Style Sheet

  Open issue #20:

  Is it OK to use a point size in a style sheet? Should we suggest that the
  page author convert all font sizes to relative units (em, ex, larger,
  smaller, or a percentage)?

  This issue comes up because of WCAG 3.4 - "Use relative rather than absolute
  units in markup language attribute values and style sheet property values."

  The guideline specifies that even style sheets use relative units, but it
  seems to me that in style sheets it's OK to specify a specific point size
  for fonts. The user can override the authors choice with their own

  CSS defines only 7 categories of font sizes (xx-small, x-small, small,
  medium, large, x-large, and xx-large) and most authors demand a higher
  granularity than that.

  I see that CSS defines font size names (small, medium, large etc.) as
  "absolute" when I would call them "relative".



Charles McCathieNevile    http://www.w3.org/People/Charles  phone: +61 409 134 136
W3C Web Accessibility Initiative     http://www.w3.org/WAI    fax: +1 617 258 5999
Location: I-cubed, 110 Victoria Street, Carlton VIC 3053, Australia
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Received on Sunday, 4 February 2001 05:50:59 UTC

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