del[datetime]::before { content: " ( "attr(datetime)"\00524a\009664) "; text-decoration: none !important; } <p><del datetime="2008-03-03T11:00:00+09:00">削除される文字列</del>テキストデータテキストデータ</p> del[datetime]::before { content: " ( "attr(datetime)"\00524a\009664) "; text-decoratio…