Now, you want to be able to hide some of those fieldsets. You could make the legend clickable.
hide_element()is dead easy. I do it in five lines. I could drop one if I wanted. Just a bit of stylesheet manipulation. But there's a problem. As written, that hides the fieldset for good. I really want to toggle. So, something must remain.
This is better, but you have to name every single fieldset. There should be a way to address everything anonymously. And there is. jQuery. Which I don't quite grok yet. But that's where my head is.