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Re: Issues with "valid CSS" code and new ZoneAlarm Pro ad blocking

From: Jukka K. Korpela <jkorpela@cs.tut.fi>
Date: Sat, 29 May 2004 08:09:37 +0300 (EEST)
To: www-validator@w3.org
Message-ID: <Pine.GSO.4.58.0405290800001.18415@korppi.cs.tut.fi>

On Fri, 28 May 2004, Keith Underdown wrote:

> I have embedded the html code given on hte site for valid webpages and
> it's giving problems with the latest release of ZoneAlarm Pro with
> Ad-blocking set to high.

The icons _are_ advertisements, are they not? So your firewall does what
you ask it to do, though imperfectly (it does not block the "Valid CSS"
image). And, of course, the ad-blocking thing is pretty primitive
guesswork, called "heuristics" by many: it looks at image sizes and thinks
that some dimensions mean that the image is an ad (and often guesses

> The Valid Html image was blocked but the CSS one wasn't,

Because the "Valid HTML" image has width and height attributes, the "Valid
CSS" hasn't. The ad-blocking software typically looks at those attributes;
it does not bother trying to parse CSS code, or analyze the actual images.

If you really want to prevent ad-blocking, just omit the height and width
attributes, without even replacing them by corresponding CSS properties.
They are only a matter of efficiency of page rendering and do not affect
the ultimate result (unless they differ from the actual image size, in
which case the image will be distorted by the browser). If, on the other
hand, you wish to improve the quality of your pages, remove the icons
(see http://www.cs.tut.fi/~jkorpela/html/validation.html#icon ).

Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/
Received on Saturday, 29 May 2004 01:09:40 UTC

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