Comparison of best-fitting model spectrum (red line) with re-normalized observation (black line; HIRES spectrum taken on December 24, 2017) with special focus on the broad He I lines 4387.93 Å (left panel) and 4471.48 Å (right panel). Light colors mark regions that have been excluded from fitting. Residuals χ are shown as well. The resulting residual pattern, namely that the observed wings are too strong while the observed cores are too weak, could be indicative of vertical stratification; see, e.g., Schneider et al. (2018) for details, or disk emission filling the line cores.