The css-ruby spec does not explicitly states anywhere that the width and height properties do not apply to the the various kinds of ruby boxes (ruby bases, ruby annotations, ruby base containers, ruby annotation containers, ruby containers).

To varying degrees, these boxes are similar to inline boxes, and the spec does refer to similarity in various occasions. We should expect these properties not to apply, and that's indeed what can be seen in Firefox, Chrome, and Safari.

Rather than relying on general but vague similarity with inline boxes, the spec should explicitly state that width and height don't apply.