[Doitsu]

Originally Posted by Hitch

What happens with those pseudo-elements on K7 devices?

They are simply being ignored. I.e. users of older devices might miss out on some features, but since they're most likely not aware that they exist in the first place, their reading experience won't be negatively affected.

For example, all that Dylan Tomorrow's CSS code does is ensure that some elements don't get indented. I.e. without fallback code the KF7 version would have some extra indents that most readers won't even notice unless they're typography buffs.
In that respect, I fully agree with the following comment by 52novels:

Originally Posted by 52novels

The developer/designer just tries to make great looking ebooks. [...]
His personal thoughts on RMSDK, which are similar to mine, is if the book ain't broke and is still otherwise well-designed, the reader's experience isn't going to be warped by pseudo-classes/webkit stuff/etc not showing up.

Originally Posted by William Ockham

@Dylan Tomorrow: I didn't mean to suggest that these CSS3 features shouldn't be used in production ebooks. I do think that folks should be aware of the risks involved. To be (perhaps overly) pedantic, KF8 doesn't support any of these features. The webkit rendering engine used by the various devices supports these features.

IMHO, you cannot be sure that KF8 doesn't officially support these features, just because they haven't been properly documented yet. As I pointed out in an earlier post, whoever updates the Kindle Publishing Guidelines doesn't seem to be the most knowledgeable person and in my personal experience some tech writers simply take the specs that they get from the developers polish them a bit and add them to the official documentation without actually fully understanding them, which can result in documentations that don't make sense.

The current version (2013.3) says:

The following CSS selectors, attributes, and properties are not supported in the Kindle format:
• E + F (Direct adjacent)
...
• E::afterCounter-incrementCounter-reset

IMHO, it's quite possible that "Kindle format" refers to Mobi7. The list also doesn't include the :not pseudo selector. I.e., theoretically book designers are not prohibited from using it.

In the absence of updated guidelines, Kindle designers have to treat Kindle source code like source code for any other programming language and interpret the absence of KindleGen warnings and error messages as an implicit acceptance of the validity of the source files.

For example, the latest version of KindleGen still displays an error message for :counter-reset and :counter-increment but not for the other pseudo elements. IMHO, Amazon could have easily added error messages for the other pseudo elements if they didn't want them to be used in Kindle books.