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Re: [css3-background] background-size and zero length

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Wed, 12 May 2010 09:01:48 -0400
Message-ID: <4BEAA6BC.50308@mit.edu>
To: Brian Manthos <brianman@microsoft.com>
CC: "www-style@w3.org" <www-style@w3.org>
On 5/12/10 3:23 AM, Brian Manthos wrote:
> Note that this example doesn't apply directly today because neither Opera nor Firefox appear to support background-size values in the background shorthand no matter what I attempt to throw at them.

Yes, because the syntax for background-size in the shorthand wasn't 
finalized as of when we implemented -moz-background-size.  I doubt we'll 
add it to the shorthand until we switch from -moz-background-size to 
background-size, for that matter.

> But let's assume they support the shorthand-based specification of background-size values in the future.  If Firefox maintains the current behavior for values less than 0.00833333331px, then the treatment of that markup will be the same in the future.
>
> Namely, IE might see...
> div {
> 	background: url(http://www.microsoft.com/favicon.ico) / 0.00833333330px 100px aqua;
> 	background-size: 100px 100px; /* override the sizing */
> 	height: 100px;
> 	width: 100px;
> }
>
> ... while Firefox would see ...
> div {
> 	background-size: 100px 100px; /* irrelevant, no image specified */
> 	height: 100px;
> 	width: 100px;
> }

Uh.... Why, exactly?  Given your style rules above, Firefox will have a 
specified value of "100px 100px" for background-size and render the 
background at that size.  I don't understand how you came to your 
conclusion; care to explain?

In fact, your rule above would be treated by Firefox exactly as this 
rule would be:

   div {
     background-image: url(http://www.microsoft.com/favicon.ico);
     background-size: 0.00833333330px 100px;
     background-color: aqua;
     background-size: 100px 100px;
     height: 100px;
     width: 100px;
   }

> Such oddities are the enemy of interoperability.

Yes, but there is no such oddity in this case.

-Boris
Received on Wednesday, 12 May 2010 13:02:31 GMT

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