A hairline space between em-dashes can be quite visually pleasing (in American writing; British uses full spaces around en-dashes). Like what Medium does. But

A hairline space between em-dashes can be quite visually pleasing (in American writing; British uses full spaces around en-dashes). Like what Medium does. But in that case I would prefer that the source text still has no spaces. Such things can be added in postprocessing.