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Re: [CSS21] Proposal to define "Block container element"

From: Anton Prowse <prowse@moonhenge.net>
Date: Thu, 02 Aug 2012 08:24:53 +0200
Message-ID: <501A1D35.6030805@moonhenge.net>
To: "www-style@w3.org" <www-style@w3.org>
CC: stearns@adobe.com
> On 15/07/2012 01:12, Anton Prowse wrote:
> The term "Block container element" is not defined in CSS21 (although
>> block container /box/ is, in 9.2.1.).  Several participants on this list
>> have expressed concern about this in the past.
>> I propose the following insertions/deletions to 9.2.1.  The changes are
>> limited to shuffling a couple of existing sentences around (untouched)
>> and introducing just two new concepts:
>> (1) The definition of "principal block-level box" is extended to
>> "principal box" for a wider range of elements (inline block, inline
>> table and table cell in addition to block-level elements).  This has no
>> effect on the rest of the spec, since the only cases where the principal
>> box is referred to is in the context of block-level elements/boxes.
>> (2) The term "block container element" is introduced to mean an element
>> whose principal box is a block container box, ie a block, list-item,
>> inline-block, table, inline-table or table-cell in CSS21.

In [1], in response to the proposal in [2], Alan Stearns asks:

> Should table-caption also be on the list [of elements which are
> block  container elements]?

Table captions are necessarily block-level, so are already included.

> Is a ::before {display:block} a "block container element"?

CSS21 uses the word "element" in a way which includes pseudo-elements. 
So the question is really asking, can pseudo-elements generate a 
principal box?  I feel that they can/should, depending on their display 
type of course.  Do you see any potential issues with that?

[1] https://www.w3.org/Bugs/Public/show_bug.cgi?id=18346#c4
[2] https://www.w3.org/Bugs/Public/show_bug.cgi?id=18346#c3

Anton Prowse
Received on Thursday, 2 August 2012 06:25:24 UTC

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