Ok, here's my css code.
This is the file that I use to replace the default stylesheet.
In this file I kept all your classes.
I change the selectors h1 to h6, p.
I add two custom classes.
(Sometimes I add more classes, it depends on the content of the book, but those are the main styles)
I have to say that in openOffice, before creating the epub, I reset all predefined styles, load my own styles and apply them. After that, my css file works nicely in my reader.