In $YDSE$ with white light

Maxima of all colours are formed at the centre of the screen, so, central maxima are white.Bright fringes of the first orderof seven colours are obtained near the central bright fringe  and so pure dark fringes of first order are formed near the centre of the screen only .  At any other point maxima of one or the other colour is obtained and so, complete darkness is  not present at other points . Fringe width of violet is minimum and so, it is closest to the centre.