[_savage]

Originally Posted by JSWolf

http://websemantics.co.uk/resources/...version_chart/

That page is very good for showing relative sizes. Also, if you prefer to use ems instead iof the keywords, it will show you what ems correspond to what keywords.

Thanks JSWolf! So here is what I have in my current stylesheet of one of the books now, and reading through related material it seems this is the right way to go.

body {
  font-size: 100%;
}
.big {
  font-size: 1.125em; /* large */
}
h1 {
  text-align: center;
  font-weight: bold;
  font-size: 2em; /* xx-large */
}
h2 {
  text-align: center;
  font-weight: bold; 
  font-size: 1.5em; /* x-large */
}        
h3 {      
  font-weight: bold;
  font-size: 1.125em; /* large */
}
p.hd { 
  font-style: italic;
  font-size: 0.8em; /* small */
  text-indent: 0;
  text-align: center;
}

No other "font-size" uses anywhere in the EPUB.