W3C home > Mailing lists > Public > www-style@w3.org > June 1998

Re: Selector "on presence of"

From: Ian Hickson <exxieh@bath.ac.uk>
Date: Thu, 4 Jun 1998 23:25:00 +0100
Message-ID: <01f601bd9007$e0524220$c820268a@hpxu>
To: Simon Richter <geier@psi5.com>, www-style@w3.org
> Would it make sense to have a selector that makes the rules apply only
> if a certain other element is present/not present?
> This could be laid out as a letter, no problem, but if the sender wanted
> to add something like a company logo, the layout would need some
> corrections, which could be made in a special rule which would only
> apply if a IMG.logo was present.

Why not just apply the rule to the IMG.logo element? (position it, etc).

However, I do like the idea of a selector which applies to elements matching
some condition based on other information gathered from the tree.

What about this: A pseudo-class like the :lang() pseudo-class, which accepts
as parameter a css selector. If the selector given as a paramter applies to
anything, then the rule applies to the main selector.

Eg:

BODY.letter:conditional(BODY IMG.logo) { margin-top: 2em; }

applies to BODY elements with class "letter" when there is an element IMG
with class "logo" in the document tree.

Other example:

BODY H1 { font-size: 200%; }
BODY H1:conditional(BODY H2) { font-size: 400%; }

H1 is twice as big when there is an H2 in the document.

This begs for another keyword - ':main-selector' or some such - which
matches the element(s) matched by the main selector.

BODY P:conditional(:main-selector + IMG) { text-align: center; }

Centers paragraphs which appear before images.


BODY FORM:conditional(:main-selector > INPUT[type=submit])
BUTTON.javascriptsubmit { display:none }

Hides BUTTON elements of class "javascriptsubmit" when they are contained by
a FORM element which contains as a direct child an INPUT element with the
"type" attribute equal to "submit".


Alternative names instead of :conditional() might be
:condition()
:present()
:selector-present()



>(BTW: Is there a
>:first-page pseudo-class?)
Yes. IIRC, @page :first {}

--
Ian Hickson
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Received on Thursday, 4 June 1998 18:25:55 GMT

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