Changing Fe I profile shapes (axes at bottom) and bisectors (tenfold expanded axes at top of each frame) across different stars. Top row: strong line in 3D models for ‘G1 V’ (long-dashed), ‘F7 V’ (medium-dashed), and ‘F3 V’ (short-dashed). Bottom row: weak line for ‘K2 V’ (solid), ’G1 V’, and ‘F3 V’. Top row: the local spectral continua are normalized to 100% at each center-to-limb position while the intensity scales at bottom are those of the stellar disk centers, showing how the limb darkening changes with stellar temperature. Bisectors (top axes) are absolute in wavelength and unaffected by blending lines; in corresponding 1D models, all bisectors appear as vertical lines at practically zero displacement.