Locations of the blue and red edges of the fundamental pulsation in the color-magnitude diagram for models of various metallicities and initial rotation rates. As in Fig. 2, thinner lines show locations of blue edges obtained with the frozen convection assumption, while thicker lines show blue and red edges obtained by taking into account the perturbation of convection flux. For Milky-Way Cepheids (left-most panel), data obtained by Evans et al. (2013) are included in addition to the data shown in Fig. 2. Data for LMC Cepheids (middle panel) are taken from Sandage et al. (2004) adopting a distance modulus of 18.494 mag (Pietrzyński et al. 2013). Data for SMC Cepheids in the right-most panel are taken from Udalski et al. (1999), in which only fundamental pulsators with reddening of E(B−V) < 0.08 mag are chosen using distance modulus 18.965 for the SMC (Graczyk et al. 2014; Scowcroft et al. 2016).