My reply somewhat goes against Jons, but only for Personal use. For production, there are publisher guidelines to follow.
But I do agree:
Do styling in the CSS ONLY
First 1em is the usual default, therefore redundant for block level tags, so those>>>Gone .
The first pass of Diaps toolbag blows away spans that only set fonts to 1em (CSS review is needed before any bulk surgery )
Where I differ, I set my body font UP to 1.2em and blow away all those 0.758 that are common from a calibre conversion .
BODY
is my baseline. Note that Jon's simple <p> works perfect for the majority of Paragraphs. IMHO Styles are for EXCEPTIONS to the defaults or baseline.
1.2 seems to be a standard default for
line-height, so why put it in most places (there are reasons, I do: Dropcap lines seem to need this to keep ugly spacing at bay.
Border and padding defaults to 0. gone. OTOH Margin seems to default to 1, so you may want to keep/adjust that.
Large and smaller fonts have their place (uses), which is why I abhor blanket destruction. If the book WAS well formatted, it only takes a couple of minutes to touch it up (via CSS) without willy-nilly destruction .
BTW This is one of the reasons I prefer Sigil for my
cleanups. It has a jump to CSS selector of the current tag. YMMV