Also, not sure what you mean by "the going web design markup language is ... CS5". What is CS5? That's something to do with Adobe, but as you noted, they are up to CS6 ... but this has nothing to do with code.
If you mean CSS3, well, yes, that's an extension of CSS2, but that's also in development and not much of it is supported by browsers yet.
SitePoint does have a book on HTML5 and CSS3, but remember that they are really for experimental use at this stage, apart from small bits that are supported in the newer, more pregressive browsers.