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Re: [css3-background] Background positioning area of root element when background-attachment is fixed

From: Daniel Tan <lists@novalistic.com>
Date: Fri, 23 May 2014 13:56:40 +0800
Message-ID: <537EE318.6040709@novalistic.com>
To: Xianzhu Wang <wangxianzhu@chromium.org>, "www-style@w3.org" <www-style@w3.org>
On 5/23/2014 3:15 AM, Xianzhu Wang wrote:
> Hi,
>
> http://www.w3.org/TR/css3-background/#special-backgrounds says
> "the background positioning area is determined as for the root element".
> However I tested several browsers (Chrome, IE10, Firefox, Safari) and
> they all seem not to conform this.
>
> Test case is like:
> <!DOCTYPE html>
> <style>
> body {
>    background-image: linear-gradient(white, yellow);
>    background-attachment: fixed;
> }
> </style>
>
> http://jsbin.com/pepufelo/1/ (gradient) and http://jsbin.com/pepufelo/2
> (real image with background-size: 100% 100%) also allow you to toggle
> between 'fixed' and 'scroll' background-attachment by clicking on the page.
>
> On my tested browsers, when background-attachment is fixed, the viewport
> (instead of the root element) is used as the background positioning
> area. I'm wondering if this behavior has been specified or is a known issue.
>
> Thanks,
> Xianzhu
>
>

I believe this is specified under 'background-origin', which says:

> If the ‘background-attachment’ value for this image is ‘fixed’, then this
> property has no effect: in this case the background positioning area is the
 > initial containing block [CSS21].

http://www.w3.org/TR/css3-background/#the-background-origin

-- 
Daniel Tan
NOVALISTIC
<http://NOVALISTIC.com>
Received on Friday, 23 May 2014 05:57:17 UTC

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