I knew something like this would be only a matter of time. I have already seen on different sites, for example, CSS code that makes h1 content look like it was in p tags, most likely to get the benefit of h1 without the user noticing that that text is different.

It probably comes down to whether the search engines have started looking at CSS files and matching style instructions to pieces of code. If they don't yet, they probably will soon. This is an interesting approach though. There was an old technique where you would set the position of the element to somewhere off screen, but browser makers killed that by resetting the negative value to 0, making it possible for users to see the content that would otherwise be hidden.

People will always be looking for new ways to game the system, and CSS will only make it easier... after all, now that the style information is in it's own file, you could probably [EDIT: Deleted]. Sure, thats definite spam, but it would be almost impossible to detect.

Also, code like this can be legitimate. Above I mentioned the old trick of moving an entire block off screen. That was developed as a JavaScript hack to make text and images invisible until called by user action, when the visibility attribute was poorly supported. An overreaction to something like this (penalizing sites that hide content in such methods, rather than ignoring the content) can result in more harm to legitimate sites than stopping spam. For example, until recently I used a similar trick to hide a form and some text about AJAX, which was then "put back" on the client side if the browser had JavaScript enabled and supported the AJAX methods I used in the page.

Steve, there are some browsers that implement some basic checking of the web page as you suggest, however the focus of the developers is more on the immediate threat to the user. This particular exploit is something that affects the SE ranking, not the end user, so it is unlikely that a browser developer will spend much time on this when they already have to keep on top of exploits and XSS attacks that can compromise the end user directly. But always an idea for a FireFox plugin...

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