Calibre conversions going wonky from EPUB to MOBI.
When the epub uses % for margin-top for chapter heads -- e.g., h1 {margin-top: 20%} -- blank pages are inserted at the start of the chapter, and some or all of the text inside the <h1> element goes missing. Even weirder, the first few words of the subsequent <p> go missing so that the chapter starts mid-sentence.
If I run the same epub through KindleGen, everything is fine.
If I replace % with em -- e.g., h1 {margin-top: 2em} -- everything is fine.
If it's dual-mobi, the KF8 portion is fine; only the mobi portion is affected.
I tried checking "ignore margins" in the Calibre MOBI Output prefs, but that didn't help.
Is there another setting I should look at?
Any help appreciated.