W3C home > Mailing lists > Public > www-style@w3.org > August 2011

Re: background-print

From: Håkon Wium Lie <howcome@opera.com>
Date: Tue, 16 Aug 2011 02:20:59 +0200
Message-ID: <20041.47083.814823.608470@gargle.gargle.HOWL>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: www-style@w3.org
Also sprach Tab Atkins Jr.:

 > >  > This doesn't work at all with the existing specificity rules, and it's
 > >  > a bad idea anyway.
 > >  >
 > >  > It doesn't work with existing specificity because normal user rules
 > >  > are below author rules, while !important user rules are *above*
 > >  > !important author rules.  You're looking for a specificity level
 > >  > *between* normal author and !important author rules, and that doesn't
 > >  > exist.
 > >
 > > We don't need any such level -- we will simply use the !important as a
 > > flag to signal that, um, something is important. Seems spot on.
 > >
 > > We basically did the same to handle non-CSS presentational hints:
 > >
 > >  http://www.w3.org/TR/CSS21/cascade.html#preshint
 > 
 > Do you mean that the user setting they choose from the print dialog
 > would have that special specificity level?

You can think of it that way. In my mind, the user setting doesn't
need to have a specificity level; in itself it's not part of the
cascade. But it would be sensitive to the difference between level 3
and 4 as defined here:

   http://www.w3.org/TR/CSS21/cascade.html#cascading-order

For example, the user setting could have three alternatives:

  1) do not print any background images
  2) only print background images marked as important
  3) always print background images

These options cannot be translated directly into CSS (due to the lack
of a 3.5 level, as you noted), but there's never really need to do so.

However, even if this is a technically feasible solution, it does
complicate the UI. And there will be liters of wasted ink due to
mis-labelings and misunderstandings.

 > That makes sense - we're
 > allowed to put things wherever we want, specificity-wise, if they're
 > not expressed in real CSS.

Right.

 > It still has the problem that we do *not* actually want the authors to
 > have ultimate control.  Thus, the user setting still needs to be more
 > powerful than what the author says.

Sure. That's in our constitution. 

-h&kon
              Håkon Wium Lie                          CTO °þe®ª
howcome@opera.com                  http://people.opera.com/howcome
Received on Tuesday, 16 August 2011 00:21:30 GMT

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