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Re: Expected behavior of background-clip property on the html element?

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 10 Jan 2011 15:50:11 -0800
Message-ID: <AANLkTi=zn3Y0PpOkX-QEhByTbN1wEa6ADMwRM3_RbqOV@mail.gmail.com>
To: Boris Zbarsky <bzbarsky@mit.edu>
Cc: Cathy.Chan@nokia.com, www-style@w3.org
2011/1/5 Boris Zbarsky <bzbarsky@mit.edu>:
> On 1/5/11 7:03 PM, Cathy.Chan@nokia.com wrote:
>>
>> What is the expected behavior when the background-clip property is
>> applied to the html element.
>
> Good question.
>
>> When I try this on the major browsers, all show the green background
>> well beyond the bottom border. Additionally, content-box behaves exactly
>> the same as either border-box (Chrome, FF, Safari) or padding-box
>> (Opera). Which is correct? I'm guessing neither, but it's not
>> immediately clear from the spec.
>
> I suspect the key part here is this, from
> http://www.w3.org/TR/CSS21/colors.html#background :
>
>  The background of the root element becomes the background
>  of the canvas and covers the entire canvas, anchored (for
>  'background-position') at the same point as it would be if it was
>  painted only for the root element itself. The root element does
>  not paint this background again.
>
> So the background isn't being painted on the box for the <html> to start
> with, hence it would seem that the background-clip of the <html> box
> wouldn't apply, unless something somewhere explicitly says otherwise.

Agreed.  The spec explicitly says that the BPA of the root element is
specially defined.  It could probably use a bit of clarification in
background-clip, just appending ", and thus background-clip does not
have any effect when specified on it." to the end of the first
sentence in that note.

~TJ
Received on Monday, 10 January 2011 23:51:07 GMT

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