Sigil is open source software for converting your work to EPUB format and it works extremely well. Converting to Kindle format is a breeze once you have a solid EPUB but some people get stuck on the ‘Flight Check’ when they get errors they don’t understand. One that is fairly common is: Attribute ‘align’ is not declared for Element ‘h1’ (or ‘p’ or any other). It will show you the section and the line where the error occurs. This is not because you didn’t align it properly in Word. It’s because it does not work in eBooks and Sigil does not recognize it.
In Word, paragraphs and headings may be aligned using code like this:< h1 align=”center” >Your Title</h1> so when you import your document, the code comes with it. The alignment needs to be stated a bit differently for a cleanly coded document in Sigil and proper conversion to an eBook. Replace the original code with this:
< h1 style=”text-align: center;” >Your Title</h1 > (without the spaces inside the brackets).
One way around this is to simply prepare your document right inside Sigil and avoid the conversion problems. You can add your work as a .txt file and do all your formatting inside Sigil. If you would rather stick to importing your document, Sigil has a Find and Replace feature that will let you change the code more easily.