I always create an Epub from docx in Calibre, but for Bookapy I also created a Mobi and PDF.
My docx document is left justified. Both the Epub and PDF that were created are left justified. However, the Mobi Calibre generated is justified (even right and left margins with spaces between words). Lazeez once told me that's difficult to read on a small device like a smart phone so I stopped doing it.
Anyone know why the Mobi came out as justified? Is there a setting in Calibre I missed?