The black art at the heart of information design in XHTML and CSS is wrestling forms into some semblance of orderliness. In building a small site for my girlfriend (more later), I spent about three times the effort that should be necessary for getting a handful of standard form fields — name, address, phone, email etc, — lined up properly. It was a relatively straightforward job in Safari, surprisingly difficult in Firefox, and just hopeless in Internet Explorer. Fields were misaligned, clearing oddly, refusing to conform to declared widths… painful.
Maybe it’s just me, but even in the days of table-based design, form elements drove me batty. I’ve never come across a reliable primer on how to bend forms to a designer’s own will — if you know of one, I’ll be eternally grateful — and I think it’s because in a medium that’s notorious for its inconsistencies, form elements are the bottom of the barrel.