:heading and :heading(<integer>#) — Selectors 5:heading(1):heading(2):heading(3):heading(4, 5, 6):heading(4, 5, 6):heading(4, 5, 6)CSS.supports("selector(…)") — non-forgiving parseSelectors use UPPERCASE values; elements carry lowercase — they still match, per the HTML spec's attribute list.
p[align=center] — [align="CENTER"]
p[lang=en] — [lang="EN"] (badge added via ::before)
p[dir=ltr] — [dir="LTR"]