Intensity in the line core of the three lines (525.0 nm upper, 630.1 nm middle, and 630.2 nm lower panel) at selected x positions (diamonds maximum intensity near boundary of FS, plus signs FS center, asterisks QS far away from FS) for models with different half-widths R of the FS. At R = 100 km, we have added the corresponding LTE values, which do not vary with FS width.