I18N GAP FIXED: Inline elements/styling break cursive shaping

See https://www.w3.org/TR/alreq-gap/#issue222_cursive

All major browser engines now avoid breaking joins in cursive scripts when a word contains span elements. It is also possible to colour a spacing character using CSS in all major browsers.

Note, however, that it is only possible to colour a combining mark in isolation in Gecko browsers.

See the gap report for information about other types of styling and their effect on joining letters.