Sigil Changing Formatting
 

I create the ePub exporting it from Mac Pages (either version 9 or the new one). I want to use Sigil to enter metadata such as description. When I open file with Sigil and then I save it, even if I did not change any content more than just opening and saving it with Sigil, it changes internal formatting. For example, it creates more space between paragraphs and aligns all objects to the left. Could anyone let me know what is causing this? Thanks.

Badcode ?

Sigil pretty prints the CODE, this changes nothing as to how it renders

UNLESS
HTML Tidy (if enabled. Hint pretty print tidy) tries to fix badly written code

Now it works
 

Thanks. This was the problem. I had the option activated of cleaning the code.

In that case I would really take a good look at the code before you do anything with the book. If you just open and save and the book is mangled, there is some serious strange code in there that is bound to give issues (except probably on iBooks...)

If the ePub you start with is ePub 3, then it will get mangled. Sigil does not do ePub 3 and can very easily mangle such.

Yet! It will do much better in the next release.