Feature Request: Default CSS class for fieldset/legend elements

If we wrap our beautiful blueprint-styled form elements with <fieldset> , it sticks out like a sore thumb.

Looking through the BP docs I don't see any CSS references for <fieldset> or <legend> elements, so I gather blueprint's CSS doesn't actually define anything for such elements.

So this is a request to give us a default fieldset/legend CSS class out of the box that we can use.

EDIT: Title and post edited for clarity