i: isolate;
  -webkit-ruby-position: under;
}
</style>

<div>zzzzzzzzzzzz</div>
<ruby class=mbp>X</ruby>
<grid>A<ruby class=mbp></ruby>B</grid>
<grid>A<ruby class=mbp>X</ruby>B</grid>
<grid>A<ruby>X</ruby><ruby><rbc></rbc></ruby>B</grid>
<grid>A<ruby></ruby><ruby><rbc>X</rbc></ruby>B</grid>
<ruby><rt><rbb>X</rbb></rt></ruby>
<ruby><rbc><rbb>X</rbb></rbc></ruby>
<ruby><rtc><rbb>X</rbb></rtc></ruby>
<rbb class=mbp></rbb>
<rbb class=mbp>X</rbb>
<rbb class=mbp><rt>X</rt></rbb>
<rbb class=mbp><rb>X</rb></rbb>

<