Mass evolution of gas, living stars, and stellar remnants as a function of time for the boxy SFH shown in Fig. 2. The orange and blue lines are, respectively, the results obtained assuming the gwIMF is given by the IGIMF theory and the invariant canonical IMF. The same colour-coding is applied from Figs. 6–11. The “all gas” includes gas outside the galaxy that is constrained by the galactic potential (see Sect. 5.1 above). Different from Fig. 5, here the simulated values at 10, 19, 20, 29... Myr are demonstrated, where star formation happens at 10, 20... Myr (see Sect. 4.1). The death of stars with a lifetime shorter than the star formation time step (10 Myr) causes the serrated shape of the lines.