[phossler]

I've seen some style sheets with classes based on usage in the book and some with classes defining the format

Other than possibly personal style, are there any recommendations, advantages, or disadvantages to the two approaches?

h1.book-title {
  margin-top: 10%;
  page-break-after: avoid;
  text-align: center;
  margin-bottom: 2em;
}
h2.book-subtitle {
  page-break-after: avoid;
  text-align: center;
  margin-bottom: 1em;
}
h2.book-author {
  page-break-after: avoid;
  text-align: center;
  margin-bottom: 1em;
}
p.title-page {
  text-align: center;
}
p.publisher-logo {
  margin-top: 3em;
  text-align: center;
  margin-bottom: 3em;
}

.nospaceafter {
  margin-bottom: 0;
}
.extraspacebefore {
  margin-top: 2em;
}
.small {
  font-size: 75%;
}
.big {
  font-size: 150%;
  line-height: 150%;
}
.verybig {
  font-size: 200%;
  line-height: 200%;
}
.superbig {
  font-size: 250%;
  line-height: 250%;
}