Calibre removes negative margins as fake

[EbokJunkie]

Created epub with negative side margins and converted to azw3.
During conversion Calibre reported removing of "fake margins" - that were all my added negative margins.
Here Kovid wrote that "...Negative margins can have perfectly legitimate uses.".
Has this point of view changed in the latest versions?

[kovidgoyal]

It has nothing to do with negativeness of the margins. A margin is detected as fake if the same margin is present on most paragraphs. If you want to prevent detection of fake margins, there is an option to do that in the conversion dialog.

[DoctorOhh]

Originally Posted by EbokJunkie

During conversion Calibre reported removing of "fake margins" - that were all my added negative margins.

If you don't want fake margins removed then uncheck the box, see attached. Image one is the per book setting that is saved if the book has been previously converted and image two is the Common Options, set for all future book conversions.

[EbokJunkie]

Thanks, but how to preserve fake margins via command line interface? I work only by command line and mobi ouput option "--mobi-ignore-margins" doesn't work.
Documentation wording is very unclear on this option:
"Ignore margins in the input document. If False, then the MOBI output plugin will try to convert margins specified in the input document, otherwise it will ignore them"
What False means? This option doesn't seem to accept any parameter values?
Just using this option still results in removing my margins.
Update:
Followed Doctor Ohh advice, unchecked option Remove fake margins in GUI and tried conversion to mobi (both). Result: no negative margins applied.
Interesting that kindlegen respects my addition of negative margins (I do this under tag *{}) but Calibre still kills them.

[kovidgoyal]

--disable-remove-fake-margins

[DoctorOhh]

Originally Posted by EbokJunkie

Thanks, but how to preserve fake margins via command line interface?

For future reference. If you work via only command line and someone shows you a GUI picture of the setting you look under that section of the CLI, in this case under ebook-convert in the Structure Detection section of the manual.

Good Luck.

[EbokJunkie]

Unfortunately, option --disable-remove-fake-margins doesn't seem to work.
Yes, message about removing fake margins goes away but resulting azw3 (converted epub->azw3) still shows wide margins.
Fed the same ePub to kindlegen - and received mobi with decreased margins.
Using Sigil, set side margins in ePub to +20pt.
Kindlegen produced mobi with very wide margins.
Calibre again did nothing to azw3, no change to original margins.
I'm adding this code (plus or minus for sign of value) to css in my ePub:

* {
     margin-left: 20pt;
     margin-right: 20pt;
}

and applying option --disable-remove-fake-margins.
Maybe Calibre doesn't accept tag *?

[kovidgoyal]

I have no idea what you are trying to do. If you want to somehow force the kindle to reduce its normal page margins, then there is no way to do that reliably. Setting negative page margins is a hack that will break in many situations.

As far as calibre is concerned, you can only do the following:

1) Set the various page margin options to less than zero, in which case calibre will not set any page margins at all

2) Disable removal of fake margins so that whatever fake margins you are using are left alone

And incidentally, using

* to set margins is extremely poor practice. If you have any nested tags at all every nested tag will get an additional margin.

[EbokJunkie]

You're right, I'm trying to cut down a bit side margins on Paperwhite, this hack is still better than jailbreaking. I already see the negative ramifications.. but for simple texts it works if applied sparingly. Thank you for your help.