Slopes of the linear fits of the colour − density relation in each panel of Figs. 7 and 8, for f_red on the left panel and f_blue in the right panel. Lines and shaded areas: VVDS observed data with error. Triangles: Omocks. Squares: Cmocks. Different colours of lines and symbols are for the different luminosity thresholds, as indicated in the labels. In each redshift bin, delimited by vertical dashed lines, all points should be considered at the same (central) x-value, but they are shifted for clarity.