Pressure-temperature profiles of two synthetic mini-Neptunes with f_H2O = 0.5 and equilibrium temperatures of 466 K (planet 503, blue line) and 326 K (planet 506, orange line). The black solid lines in the background are the phase boundaries of pure H₂O given by the AQUA EOS (Haldemann et al. 2020). Both planets have a similar mass of approx. 1.5 M_⊕, but different sizes due to the different physical state of water (planet 503 is a steam-world, with R_P = 1.690 R_⊕ , and planet 506 is a condensed-water world with R_P = 1.657 R_⊕ ). The red and green curves correspond to planet 503, but the equilibrium temperature was reduced to see where the transition from steam to condensed-water world occurs.