Colours and sSFRs as a function of the M_Star (left and right panels, respectively) for the simulated SDGs (filled circles coloured according to the dynamical B∕T ratios). Observational results for isolated ETGs (black asterisks; Hernández-Toledo et al. 2010) are included. In the left panel, blue and red galaxies are separated by the black line reported by Lacerna et al. (2014), while in the right panel the black line depicts the limit between star-forming and passive galaxies (Lacerna et al. 2014). Galaxies that are blue and star-forming at the same time are marked with black open squares.