It seems to have to do with what fonts are installed locally, not with the HTML version. My current browser shows ASCII 253 and 254. Numbers 256-258 show as question marks, as they must, because 255 is the highest number that can be specified with eight bits.

"É" -- É "Ó" -- Ó "Ê" -- Ê "Ô" -- Ô "Ë" -- Ë "Õ" -- Õ "Ì" -- Ì "Ö" -- Ö "Í" -- Í "×" -- × "Î" -- Î "Ø" -- Ø "Ï" -- Ï "Ù" -- Ù "Ð" -- Ð "Ú" -- Ú "Ñ" -- Ñ "Û" -- Û "Ò" -- Ò "Ü" -- Ü