CMD showing empirical IS edges (red empty circles) separately for SMC (left panels) and LMC (right panels) for 1O (upper panels) and F (lower panels) Cepheids. The black empty circles represent the median value of the intrinsic color of each bin of the corresponding sample. Fits for the blue and red edges, considering changes in slope at different pulsation periods, are shown as solid blue and red lines, respectively. Gray-shaded areas mark the blue loop extent (delimited by its bluest extreme and the tip of the RGB) for evolutionary tracks with representative Z for the SMC and LMC galaxies. The gray areas are created using tracks from 2 to 7 M_⊙ for the SMC, and 3 to 7 M_⊙ for the LMC. The upper limits for the areas are defined by the evolutionary tracks for 7 M_⊙ and would extend farther up if tracks for higher masses were considered.