[Steven630]

.....

I used Calibre to convert an AZW3 file into mobi, with extra CSS

p {  line-height: 1.718em }

to change the line-height and chose "both" as the output file type.

I sent the file to my amazon email address. The file was delivered to my Kindle, but the line-height did not change.

When I chose "old" as the output, the line-height did not change.
When I chose "new", the file could not be delivered via email.
When I converted it into AZW3 and loaded it onto my kindle since Amazon email does not recognize AZW3, it worked.

But if I

1. use Kindle Unpack to unpack the same AZW3 file
2. change the line-height in the CSS file
3. use KindleGen to generate a mobi file (select the opf file and pack up)
4. send this mobi file to my Amazon email address

I get the file and the line-height is what I want.

They are both mobi files, why the one converted by Calibre and sent to Amazon via email does not work?

I guess there must be something with Amazon cloud that somehow "corrupted" the file. But why wasn't the file generated by KindleGen "corrupted"?

This problem has existed for a long time. Thank you so much.