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Re: [CSS21] Floating - who's right?

From: fantasai <fantasai.lists@inkedblade.net>
Date: Fri, 04 Feb 2011 17:08:29 -0800
Message-ID: <4D4CA30D.3000103@inkedblade.net>
To: Васил Рангелов <boen.robot@gmail.com>
CC: www-style@w3.org, Tantek Çelik <tantek@cs.stanford.edu>
On 02/04/2011 04:22 PM, Васил Рангелов wrote:
> Hello CSSWG.
>
> I recently found something resembling a bug related to floats... but the
> thing is two implementations do it one way, and two others do it another
> way, so I don't know who's right and who's not. I hope that if I bring
> the issue here, implementers would be able to resolve who's to fix what.
>
> The problem is that a relatively positioned box with a clear inside it
> turns out on top of a statically positioned left floated box preceding it.
> Or at least that's what the latest public builds of Gecko (Firefox 4b12)
> and WebKit (Crhome 9.0.597.84 and Safari 5.0.3) do. Here's a reduced test case:
>
> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
> <html xmlns="http://www.w3.org/1999/xhtml">
>      <head>
>          <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
>          <title>TEST</title>
>          <style type="text/css">
>              .floated {float:left;}
>              .positioned {position:relative;}
>              .cleared {clear:both;}
>          </style>
>      </head>
>      <body>
>          <div class="floated">
>              <a href="#">click me if you can</a>
>          </div>
>          <div class="positioned">
>              <div class="cleared"></div>
>          </div>
>      </body>
> </html>
>
> In the above mentioned browsers, the link is not clickable because of this.

Try giving the positioned element a border or a background, and you can
see what's happening. A relatively-positioned element is rendered above
any non-positioned elements, so it's placed over the float. The reason
the link is clickable in Opera is because it lets clicks pass through
a transparent background. Give the positioned div a background, and it
won't be clickable anymore.

CSS2.1 doesn't define click behaviors, so there's nothing there that says
whether one behavior is right or wrong. But Tantek is working on defining
click behaviors in the CSS3 UI spec, so hopefully he will consider this
testcase.

> Personally, I find the IE/Opera way more intuitive. I've found several
> workarounds to make Gecko/WebKit behave like them (e.g. surround the
> floated div with another div that is to match the position of the
> positioned div, whether that means settings both to relative or static),
> but I still never figured why this occurs and what the specification
> requires. I was unable to find anything about that, though then again,
> maybe I haven't looked hard enough.

Try giving the float position: relative; z-index: 1. That will raise it
above the relpos'd element.

~fantasai
Received on Saturday, 5 February 2011 01:09:01 GMT

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