[akaBruce]

For those studying a language that might use benefit from this, I have this CSS in my Anki cards. I use the ruby tag to remind me of readings for things that aren't the main focus of the card I'm working with. For example, if a vocab word is used in an example sentence, but one of the other words in the example is unfamiliar to me.

It shows the rt tag on hover or focus and works for me for both mouse and touch on Anki and AnkiDroid. Maybe this or some variation might help others as well.

  ruby {
   text-decoration: underline dotted;
  }
  ruby rt {
   visibility: hidden;
  }
  ruby:hover rt, ruby:focus rt {
   visibility: visible;
  }