Top panels: different shapes of near-core mixing profiles for a star with a mass of 12 M_⊙ near the ZAMS. The convective core is indicated in grey, the near-core mixing region in blue, and constant diffusive mixing in the outer radiative envelope in green. Bottom panels: temperature gradients in the same region as the top panels. In each figure the insets are zoomed in on the same region of m/M_* and D_mix to show the differences at the edge of the core mixing region more clearly.