Ok I entered the code as suggested earlier in the thread and ... nothing. The cover is just as stretched as it was before. So even more confusion with css and codes. Why if instructed to display the image differently, the image keeps being twisted (but not on my computer) ...
I guess this shows that simply putting code that works for a book into another book is not necessarily going to work.
Well we tried, thanks for the help anyways
It's no big deal as the book is perfectly readable, it's just annoying to see that deformed cover but luckily this issue is with one book only.
Like I said, I'll stick to basic css stuff which I seem to graps, like indents, margins, paddings, orphans and windows and their values which I can change.