Here's an extract from my stylesheet file:
div.book {
margin-top:0.1em;
margin-bottom:0.4em;
font-family: serif;
}
...this expresses "white space" in ems, so it doesn't matter how large or small a font the user selects, the white space between paragraphs remains fairly proportional. I don't like paragraph indents ( perhaps because I'm Australian, we like things kept simple? ) but this could easily be added. The overall white space between paragraphs is 50% of a normal line of type, not 100% as would happen using standard html <p> tags.
And here's another one:
span.cap {
font-size:1.5em;
font-weight:bold;
line-height:90%;
}
Drop-caps for starts of break-points don't work very well with re-flowable text, but a larger-size cap works well, 150% bigger than whatever size the user has selected for body text. The 90% line-height is to reduce the gap reserved for "descenders" and avoid gaps between lines #1 and #2.