[FelixKrull]

Hello there,

I’m converting EPUB files to AZW3 using Calibre and I’m trying to establish best practices for clean, consistent Kindle output (no unusual page borders, no forced fonts, proper margins, etc.).

However, I’m running into several recurring issues:

Inconsistent line height
Even with the same Kindle device and identical reader settings, different converted books show noticeably different line spacing. Some books look compact, others much more airy, although the font size and line spacing settings on the Kindle are the same.

Embedded fonts overriding Kindle fonts
In some cases, books continue to display their original embedded font on first opening, even though I select a default font on the Kindle (Atkinson Hyperlegible). This does not happen consistently across all books. Workaround: I go to font settings, then chose one of the standard font once, then chose my font - then it works)

Excessive page margins / page border look
Some converted books still have larger margins then others, giving the impression of a page frame, even when Kindle margin settings are set to minimal.

I assume this is caused by CSS rules in the source EPUB (line-height, margins, padding, body width, etc.), but I would like to avoid manual editing for every book if possible.

Questions:

What is the recommended Calibre conversion setup for EPUB to AZW3 to ensure consistent line height, no forced fonts, and minimal margins without page borders?

Is it better to rely on Calibre’s Look & Feel / Styling options, or to clean and normalize the EPUB CSS beforehand?

Are there specific CSS properties that Kindle tends to ignore or handle differently, such as line-height, margin, padding, or @font-face rules?

Any practical advice or proven workflows would be greatly appreciated.

Thanks in advance!

(Note: I am not a native speaker and made this post with ai help, hope that is ok)