I was made aware of https://www.w3.org/TR/css-text-3/#small-kana and after some research it appears this isn't backed by data in Unicode. That makes me a little nervous.

@frivoal would you be up for asking Unicode through http://unicode.org/reporting.html to see if they would be willing to take over maintenance of this mapping? That way it will also eventually make its way into ICU and similar tooling and we can be more confident it'll be consistent and correct over time.

Thanks!