The lh and rlh length units (computed line heights) are useful if you want to maintain vertical rhythm, which printed books typically do.
Unless a book has lots of images, headings are the main culprits breaking vertical rhythm. They offset the lines below them by an arbitrary amount, making the last line closer/farther to the bottom of the page than on normal body-text-only pages. Two-column mode is especially an eyesore with lines on either side not lining up.
If the rlh unit was available, a style tweak h1 { min-height: 5rlh; margin: 2rlh 0 0; } could set things right.
The
lhandrlhlength units (computed line heights) are useful if you want to maintain vertical rhythm, which printed books typically do.Unless a book has lots of images, headings are the main culprits breaking vertical rhythm. They offset the lines below them by an arbitrary amount, making the last line closer/farther to the bottom of the page than on normal body-text-only pages. Two-column mode is especially an eyesore with lines on either side not lining up.
If the
rlhunit was available, a style tweakh1 { min-height: 5rlh; margin: 2rlh 0 0; }could set things right.