Comparing the HTML of version 6.8 with version 7.2, I see that many classes got new names. This means that we essentially have to rewrite our custom CSS file, which is not fun.
What about providing a script ``` texinfo-css-update --from 6.8 --to 7.2 < infile > outfile ``` that does the job, reporting conversion problems that have to be resolved manually? There could also be an option `--compatible` to allow the CSS file work for both an older and a newer `texi2any` version. Werner PS: LilyPond provides the script `convert-ly`, which does exactly what I've suggest above, namely to update syntax changes in different LilyPond versions. https://lilypond.org/doc/v2.25/Documentation/usage/updating-files-with-convert_002dly