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Re: [CSS21] Another ambiguity in the definition of "containing block"

From: Giovanni Campagna <scampa.giovanni@gmail.com>
Date: Sun, 27 Sep 2009 22:45:19 +0200
Message-ID: <65307430909271345t50a6c3d5u5d65ea099565f1ae@mail.gmail.com>
To: Boris Zbarsky <bzbarsky@mit.edu>
Cc: www-style list <www-style@w3.org>
2009/9/27 Boris Zbarsky <bzbarsky@mit.edu>:
> Consider the following testcase:
> <!DOCTYPE html>
> <body>
>  <div style="height: 200px;">
>    Text
>    <div style="float: left; height: 50%; width: 100px;
>                background: green"></div>
>    More text
>    <div>x</div>
>    Text
>    <div style="float: left; height: 50%; width: 100px;
>                background: orange"></div>
>    More text
>  </div>
> </body>
> In current browsers I see the following behavior:
> Gecko: Two floating 100px by 100px squares (one green, one orange).
> Opera 10: As Gecko.
> IE8: As Gecko.
> Webkit: No visible squares; the offsetHeight of the floating divs is
> reported as 0.
> If the "<div>x</div>" is removed, then Webkit's rendering changes to match
> the other browsers.
> I believe the issue is a disagreement over section 10.1 item 2.  Webkit is
> using the anonymous block box created per section to contain the
> text as the containing block for the float.  If one assumes that the float
> and the text around it have the same ancestor boxes (which seems like an
> eminently reasonable assumption), then this interpretation makes sense.  If
> this item is not actually talking about boxes but rather means "the box
> generated by the nearest block-level ancestor element", then it's just
> ambiguous as to which box is meant here.

Even if it used the anonymous box (which includes "Text" and "More
text"), the float should have been half the height of that box (not
zero, because it is not empty), that is half the line-height. So it
maybe a different bug.
In any case, imo the interpretation "the box generated by the nearest
block-level ancestor element" is the correct one (also because
everyone but webkit read it that way), and it is not ambiguous, since
the 200px wide div generates only one box, the anonymous one is
generated by its content.

> I still think that all of 10.1 is ambiguous in any but the most trivial
> cases that fall under item 2; this is just another example....

Well, replacing "ancestor" with "ancestor's" may solve it, I think.

> -Boris

Received on Sunday, 27 September 2009 20:45:54 UTC

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