Upper panels: Cluster–galaxy CCFs derived from the IllustrisTNG300-1 simulation. The black curve shows the full galaxy sample; blue, green, and red curves correspond to the respective colour subsamples. Rows correspond to terciles of galaxy system M₂₀₀, and columns to terciles of galaxy stellar mass. Shaded regions show uncertainties estimated via jackknife resampling. Lower panels: Ratios between the CCFs of the red, green, and blue subsamples and that of the total sample. Dashed grey lines denote the median R₂₀₀ corresponding to each tercile of M₂₀₀.