Using colon in time format yield to miniscule font

[kuon]

If I use a colon as time separator, it yield to a minuscule font (see photo).

[[keys]]
  index = 0
  [keys.widget]
    id = "button"
    [keys.widget.config]
      label = "Music"
  [keys.action]
    deck = "music.deck"

[[keys]]
  index = 3
  [keys.widget]
    id = "time"
    [keys.widget.config]
      format = "%H:%i;%s"