[BetterRed]

@firemouz, as itimpi says, paper size is irrelevant

In Word don't use tabs, and don't use blank lines to create vertical space - use paragraph formatting and/or Word's Styles instead

Also don't insert any page or section markers.

And try saving the file as Web Page Filtered in Word rather than docx and then getting Calibre to convert the HTML to Epub (Calibre will put the HTML in a zip when you add it, but don't let that worry you). HTMLZ, as its known, can often produce better results.

BR