Stokes number of the pebbles in the simulations presented in Figs. 15 and 16 at a given time t and orbital distance r in the disc. The black lines mark Stokes numbers of 0.05 to 0.4. Note that each planet growth trajectory stars at a given point in r-t and the planet the moves to higher time values, indicating that the Stokes number of the pebbles accreted by the planet increases. Additionally, the planet migrates in the disc to smaller orbital distances, which also increase the Stokes number of the accreted particles. The over-plotted blue lines correspond to the growth tracks shown in Fig. 14, where the solid line corresponds to solid (pebble) accretion, the dot marks the pebble-isolation mass, and the dashed line corresponds to the gas accretion phase. The planetary growth track moves upwards to increasing time.