Like with the CSS Zen Garden HTML, it might be useful to easily re-style the web page/site without altering the HTML code.

However, I personally try to keep my HTML as lean as possible and very rarely add elements through DOM scripting (depends on the purpose, of course). When it comes to interaction, my standpoint is pretty clear in my post you linked to.

It is not impossible to do with CSS (and have it degrade gracefully) and perfectly valid (and semantic) markup, so why sully the document, even is it is via the DOM

I believe the answer lies in context. Inserting extra elements via the DOM might be a solution to be implemented when you want your content to stay as clean as possible - perhaps if someone else is maintaining the content? I can see where keeping the extra hooks out of it makes sense in that case as it makes it easier for the novice to maintain. Having said that, I wonder if it really makes much difference - I mean, what happens if JS is off? It still degrades gracefully. If CSS is off or not supported, what happens? again, it will still work.

Perhaps it is an issue of convenience then, for the developer? If the technique I choose has little to no impact on the people viewing the site, and it helps me, then why not?

I’ll probably make a post on it soon, because it’s too much to stuff in a comment here. In short, though, I think that -some- level of purism is great, but it shouldn’t be taken to extremes. Adding markup for design hookups is sometimes inevitable, because CSS still has a fair amount of limitations. See my site right now for an example (current latest post has a bit about it, too)

Regarding the comment preview issue, the only thing I can figure is that it was part of the comment preview I have been using (ComPreVal), coincidentally co-authored by one Mr. Mark Wubben ;-)

I didn’t have the time to figure out the error, so I rewrote the form and switched over to one of the live preview plugins (Live Comment Preview) and everything seems to be working pretty well now. That said, I think I may alter the form a little more later to offer a preview fallback for those who do not have JavaScript enabled.

As for the <br /> vs. <p>, I’m new to WordPress and I hadn’t noticed that, but I will work on fixing it.

Actually I think :hover should be behaviour if you want to build things more advanced than a simple a:hover with it. The support is simply not there to do that using CSS (and there are other downsides, too), but it is by far the easiest and most reliable solution for a tags.

As for inserting non-valid elements into the DOM: only as a hack. But the thing is, you need this hack! If you want to insert Flash movies using the DOM object won’t save you.

At the end of the day I’d like to be a pragmatist who solves the problems for virtually all browsers, instead of a theorician which gets it to work the right way in but a few.