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

Re: Shadows vs. layout

From: fantasai <fantasai.lists@inkedblade.net>
Date: Mon, 03 Aug 2009 10:23:12 -0700
Message-ID: <4A771D00.5080309@inkedblade.net>
To: Brad Kemper <brad.kemper@gmail.com>
CC: W3C style mailing list <www-style@w3.org>
Brad Kemper wrote:
> I recently discovered something while attempting to use box-shadow that 
> I found frustrating, and I am not sure if it is a bug or something that 
> CSS addresses or should address. I could not find anything in the spec 
> that addresses the issue:
> 
> It is my understanding that box-shadow is not supposed to affect layout. 
> However, when I have a shadow in an element that is positioned close to 
> the right side of the page, and the shadow is offset to the right, it 
> can actually cause the page to become wider, and create horizontal 
> scroll bars. Positioning the element and the shadow to the left does not 
> share the same problem. [1] Text-shadows DO show the same sort of 
> behavior. [2]
> 
> This seems like the wrong behavior to me. Aside from the fact that an 
> absolutely positioned item is also not supposed to affect layout, and 
> does anyway, the purely visual effect of a shadow is such an ephemeral 
> thing that it should never, ever, affect layout. I just can't imagine a 
> situation where I would want the page to become wider because I added a 
> shadow to it.
> 
> I found this problem while trying to recreate the rather largely blurred 
> shadows of Mac OS X, and discovered that it limited how close to the 
> right side I could get without having a scroll bar appear. There didn't 
> seem to be any other way around it without changing the overflow 
> properties of the container block to hidden and giving it a fixed width, 
> which was not an option for me.
> 
> I didn't find anything in the spec about the meaning of "does not affect 
> layout", but I think for the shadow properties at least it should 
> elaborate that adding a shadow does not increase the size of its 
> container in any circumstance.
> 
> [1] http://www.bradclicks.com/cssplay/shadow_vs_layout.html
> [2] http://www.bradclicks.com/cssplay/text-shadow_vs_layout.html

I completely agree. Added
   "Shadows never affect layout, and do not trigger scrolling."
to the spec, hopefully that's clear enough.

~fantasai
Received on Monday, 3 August 2009 18:23:54 GMT

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