W3C home > Mailing lists > Public > www-style@w3.org > March 2009

Re: CSS3 missing selector

From: Brad Kemper <brad.kemper@gmail.com>
Date: Mon, 23 Mar 2009 09:57:26 -0700
Cc: Dave Smith <smithd7@tcd.ie>, www-style@w3.org
Message-Id: <5FA08FBC-12BF-420B-BFD4-324F0205E76D@gmail.com>
To: Giovanni Campagna <scampa.giovanni@gmail.com>

On Mar 23, 2009, at 9:16 AM, Giovanni Campagna wrote:

> 2009/3/23 Brad Kemper <brad.kemper@gmail.com>:
>>
>> On Mar 23, 2009, at 6:15 AM, Giovanni Campagna wrote:
>>
>>> 2009/3/23 Dave Smith <smithd7@tcd.ie>:
>>>>
>>>> Hi www-style
>>>>
>>>> I believe there is a useful and yet missing selector. I'll  
>>>> explain by a
>>>> rough example:
>>>>
>>>> <section>
>>>> <h1 or h>My section heading</h1 or h>
>>>> <p>Para</p>
>>>> <p>Para</p>
>>>> <p>Para</p>
>>>> <p>Para</p>
>>>> </section>
>>>>
>>>> Given the above, to style the section content so that it is  
>>>> indented by
>>>> 20px, but leave the heading with no margin can be done with:
>>>>
>>>> ..section > *:not(h1) {margin-left:20px;}
>>>
>>> You could also use ".section > p"
>>
>> Not unless you are sure that all of the block-level content at that  
>> level is
>> going to be paragraphs, on all of the pages you apply the style  
>> sheet to.
>
> His example was rather short and specific (and usually you want to
> indent paragraphs, not tables)

Examples on a mailing list tend to need to be pretty short. I think  
the general idea is to be able to separately style the content that  
the heading refers to. In this case its not really indent he wants  
(even though he used that word), its margin-left, which could be for  
tables, lists, DIVs, etc.

>>> (or negative margins, or text-indent, but this is not relevant to  
>>> the
>>> selector)
>>>
>>>> but what if the following could be done:
>>>>
>>>> h1:content {margin-left:20px;}
>>>> A pseudo element wraps the content, based on heading scope, and  
>>>> is then
>>>> styled.
>>>>
>>>> and
>>>>
>>>> h1:section { }
>>>> A pseudo element wraps the heading and content, based on heading  
>>>> scope,
>>>> and
>>>> is then styled.
>>>
>>> 1) Pseudo-elements use two colons: "::section" and "::content"
>>> 2) It should always be avoided having pseudo-elements targeting real
>>> elements (instead of CSS generated ones)
>>
>> It could just as easily be a CSS generated wrapper that was more  
>> similar to
>> h1:content , but also included the heading.
>
> What do you mean wiht "also included the heading"? What boxes should
> the pseudo-element target / create and what should the resulting CSS
> tree look like?


<section>
     <anon for="h1::content-parent">
         <h1>My section heading</h1>
         <p>Para</p>
         <p>Para</p>
         <p>Para</p>
         <p>Para</p>
     </anon>
</section>

<section>
     <h1>My section heading</h1>
     <anon for="h1::content">
         <p>Para</p>
         <p>Para</p>
         <p>Para</p>
         <p>Para</p>
     </anon>
</section>



>>> 3) Something similar to this was already proposed [1]:
>>
>> Usually when the same general idea keeps coming up from different  
>> people, it
>> is because there is a perceived need or benefit.
>
> In fact, I do agree that I would be a very good feature to have.
>
>>> :heading(<level>)
>>> pseudo-class to select elements that estabilish an heading at that
>>> level (according to the relative language)
>>>
>>> :section(<level>)
>>> pseudo-class to select elements that estabilish a section at that
>>> level (according to the relative language)
>>>
>>> For example, :heading(2) matches "h2" or  "section > section > h" in
>>> XHTML2
>>> :section(1) matches "body" in HTML5
>>>
>>>> Apart from being easy to read, one possible advantage is in  
>>>> backwards
>>>> compatibility with old documents (without section elements) that  
>>>> they
>>>> could
>>>> be styled just as easily as new ones. Plus it just feels good, at  
>>>> least
>>>> to
>>>> me.
>>>
>>> Well, old documents don't use new features, so they won''t get much
>>> benefits from this.
>>
>> Sure they do. All the time. It is often possible to have a new CSS  
>> file when
>> it is not possible to replace all the HTML on an entire site.
>
> I'm not sure about that,

I am. I deal with a site with hundreds of pages, and when it is time  
for a redesign, it is mostly in the CSS file. I sometimes have to do a  
"find and replace" on snippets of HTML that occur throughout the site,  
but clearly that is the less desirable thing to do, and mostly has to  
do with very old code, or a change in non-strictly-presentational  
elements. The modern ideal is for presentational styling to be all in  
the CSS, so that CSS is all you need to change to do a redesign (aside  
from redesigning the navigation, etc.).

I also have to sometimes create CSS files for partner sites, where I  
have NO control over the HTML, but can provide style sheets for the  
look, feel, and branding (the sales reps always say "it can look just  
like it is part of your existing site!").

> and consider that in plain HTML4 it is easier
> to write "h4" than ":heading(4)",

I don't understand your point here.

> but this is definitely not relevant:
> once a feature is specified and implemented, it can be used
> everywhere.

Right. What matters is the feature being in common UAs, not so much  
about old HTML documents.


>
>
>>>> all the best
>>>> Dave
>>>> ---
>>>> Dave Smith, 01 896 3976, smithd7@tcd.ie, Trinity Web Office
>>>> Please CC the Web Office, webdes@tcd.ie, in correspondence
>>>> Please note that electronic mail to, from, or within the College  
>>>> may be
>>>> the
>>>> subject of a request under the Freedom of information Act
>>>>
>>>
>>> Anyway, Selectors Level 3 is currently a Last Call WD, so new  
>>> features
>>> won't be accepted. You should wait until Selectors Level 4.
>>
>> Its not too arly to start making a list of things we'd like to see in
>> Selectors Level 4, is it?
>
> Well, there is already one at <http://wiki.csswg.org/spec/selectors4>
> but I still think that it is too early to talk about Level 4.

So, apparently csswg.org disagrees with you.

>
> Selectors Level 3 are yet to finish.

This is a well known statement of fact, yes. But they are nearly  
finished, and it is good to know that ideas for CSS4 selectors are not  
being ignored.

>
>
>
> Giovanni
Received on Monday, 23 March 2009 16:58:03 GMT

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