Ah, sorry again - I didn't see the ebook attachment on your earlier post.
I can't speak to Lithium's fidelity, perhaps someone else is more familiar with that app. However, the line-height appears to be coded properly in your css. I've attached two images where I added a border to visualize the differences between 2 and 5 line-height and it reacts properly.
.rtltext {direction: rtl; line-height:
5; border:1px solid red}
What exactly is incorrect with Lithium's display?