I hate that so many publishers/authors build their eBooks without using the basic standard HTML tags. Instead of using H1, H2, H3 many use a P tag with a gosh-awful CSS class call out. HELLO, that makes autocreation of TOCs a no go!! I personally like a minimalist approach to CSS within eBooks. If I have to modify a book, the first thing I do is strip out all the garbage from the CSS file. No need to remove the CSS classes and what not from each HTML file as it will be ignored if it cannot be found in the CSS file. Next I make sure each chapter/section heading has an H1 or H2 tag. If it is not to much work I also make sure all subheadings have a heading tag as well. It usually isn't too time consuming, but some publishers seem to use a different class for every subheading (within the same level) making a search replace impossible. Idiots!