Very nice work. Some comments: - "Make sure to set letter-spacing: 0 when working on a multilingual layout" is an advice that's too strong. Letter spacing brea

Very nice work. Some comments: - "Make sure to set letter-spacing: 0 when working on a multilingual layout" is an advice that's too strong. Letter spacing breaks only with connected scripts, Arabic or Devanagari. (And it's a bug, Arabic script users make use of letter spacing heavily in real life.) Most other scripts - CJK, Cyrillic, Greek, Hebrew, Georgian - will work just fine with letter spacing, and it will have the same meaning as in Latin. But - just as with line height, letter spacing value sometimes needs to be customized. - You probably don't need to flip the "?" icon for Hebrew users, they don't flip it as in Arabic. - Arabic letters being rendered over themselves with custom opacity is an unfortunate bug in Webkit. Firefox doesn't have it. But yes, this means that font opacity has to be used sparingly until it's fixed.