How can I highlight certain parts of a ruby text?

I’d like to highlight certain kana in the ruby text above Chinese characters in order to indicate reduced vowels. Can this be done?


The character style applies to all the ruby text. The only workaround I can think of would be to enter a specific ruby text for each vowel so to apply a dedicated character style.

Nevertheless, the cumbersome of this workaround seems to make it almost unusable, sorry…