ruby { ruby-position: over; }

<p lang="ja"><ruby><rb>紙</rb><rt>かみ</rt><rb>芝</rb><rt>し</rt><rb>居</rb><rt>ばい</rt></ruby></p> <p lang="ja" id="vertical"><ruby><rb>紙</rb><rt>かみ</rt><rb>芝</rb><rt>し</rt><rb>居</rb><rt>ばい</rt></ruby></p>