Does your feature request involve difficulty completing a task? Please describe.
Currently, it's impossible to position <ruby> text with ruby-position

Describe the solution you'd like
All of the properties of ruby-position would be supported

Describe alternatives you've considered
If it proves to be too difficult to implement technically it should be fine to implement just the over and under values and/or the -webkit-ruby-position property with its before and after properties (corresponding to over and under respectively)