And there are eBooks that use a span such as...
<p>This is an <span class=italic>italicized</span word.</p>
With the CSS being something like....
.italic {
font-style: italic;
}
However, there are times when an italic is used in a class when the entire paragraph is italicized. and <i> when not.
So if you are of the type that believes in <em> (I don't). Then you have have to edit all of this manually.