Don't tell the CSS zealots, but mainstream eBook readers (for the XHTML-based EPUB) basically throw the CSS away and reflow everything anyway based on a generic

Don't tell the CSS zealots, but mainstream eBook readers (for the XHTML-based EPUB) basically throw the CSS away and reflow everything anyway based on a generic prose style with a heavily optimized serif and user preferences for font size. Most importantly, they're applying proper hyphenation and justification, as expected by book readers and unsupported by CSS for a much better reading experience compared to browsers. The extent of this might not be readily apparent in English language publications (with relatively short words and long phrases), but in German almost every other line has hyphenated words at the end (and I'm guessing in other languages with long composed words such as Finnish or Hungarian as well). EPUB uses extra tags for eg. spreading (responsive layout) anyway. Reading EPUB 3 specs is almost comical when compared with the feature set of real world EPUB publications and reader software: CSS trickery (such as pointless SVG wrappers around raster images), yet not using floated elements even for the few cases where it's a good fit (initials, flowed images), using Unicode quotations and mdash/ndash, not using CSS paged media for pagination and line numbering, EPUB 3 reference examples crashing reader software, Amazon and Apple using proprietary EPUB extensions for these reasons anyway (and having good technical reason to) while not contributing to W3C, Inc's spec., ... The last useful EPUB spec version appears to be 3.0. from 2014 before IDPF merged into W3C, Inc. Later versions reference the "HTML living standard" and CSS snapshots (with CSS-everything that no reader software is going to support, ever). To bring old reference examples into compliance with 3.3/epubcheck, the only thing the WG bothered to do was to put secondary headings into <p> elements where they used <h2> in <hgroup> to match the changed spec (removal of the so-called HTML outlining algorithm). Great so this makes the reference examples nominally conformant, but leaves the installed base of eBooks out there without backward compatibility (and e-readers are far from evergreen browsers). Not that it matters anyway: calibre's conversion manpage strongly recommends and defaults to EPUB 2 anyway, supporting EPUB 3 only since 2019. In a way, EPUB 3.3 with its generic forward compat reads like the last spec its authors intend to publish, before the major organizational and funding changes at W3C, Inc in 2023. I'm seriously beginning to wonder if PDF is the better format for reading and archival after all as 7+ inch reading devices become the norm (or don't they?)