Size–mass relation for JKCS 041. Lines show the mean fitted model and its uncertainty (solid line and yellow band), along with the intrinsic scatter (dotted line). Points are color-coded according to their location in the age–mass plane (Fig. 7): older (red) or younger (blue) than the mean relation by at least 1σ_intr, with black points indicating galaxies within ± 1σ_intr the mean age–mass relation.