links for 2008-12-03

Obscure HTML element of the day: dfn

I’ve had an opportunity to do a little static HTML + CSS work recently, and have had a few educational and reeducational moments about the joys of doing basic web development–all the stuff that a good CMS like WordPress hides from you.

Today’s educational moment was a question of footnote treatments. My application had footnotes at the very bottom of its page, with nothing beneath them, and did inpage links to the footnotes. But it was linking to the footnotes from a part of the text that was close to the bottom of the page, so the footnote was already visible. As a result, when a user clicked a link to get to the footnotes, nothing happened–the footnote was already there, and there was no more page to scroll up.

There are ways around this. Daring Fireball has a lot of empty space on its pages below its footnotes, meaning that the page can scroll to place the footnote at the top. But the bug got me thinking again about why I was doing the footnotes and how I could change the user experience. What if I moved the footnote text–which was generally some sort of quick definition–into a mouseover? I knew I could do it with acronym, but the text I was footnoting wasn’t an acronym so it wouldn’t have been semantically correct. Was there a semantic way to mark up the word or phrase being footnoted so that when moused over, a definition would show?

Enter dfn. See what that does? The dfn tag is basically tailor made for what I wanted to do, and is even reasonably well supported. FF3 and IE7 even automatically italicize the term.

I made one more change to my stylesheet to make it really explicit that more information was there for the mouseover, and applied the same rule that I had for abbreviations:

dfn {
   border-bottom: 1px dotted #333;
   cursor: help;

With that, the user got a dotted underline on the term, and a help cursor when they moused over.

I would probably make one more change if the application was expected to be printed, which would be to introduce some styles or JavaScript in the print stylesheet that would do an inline expansion of the definition. But for what I needed to do, dfn worked pretty well by itself. Yay obscure HTML elements!