[racket] Sintrapara styling?

Questions on Scribble:

We're in the middle of customizing how our Scribble documents look in
the browser.  One of the structures we see are Sintrapara elements.
Is it safe to override the styling of these?  When are they introduced
into the document structure, and what role do they play?  Also, we see
a lot more <p> paragraph elements than we expected to see; what rules
specify when a paragraph element is being introduced?  For example,
we're seeing them in every @item of an @itemlist, and don't understand
why.

Thanks!