HD 34078 (O9.5 V): comparison between the observed spectrum (black) and synthetic spectra (coloured) for selected diagnostic lines of H, He, C, N, O, Mg, and Si. The synthetic spectra were computed with FASTWIND using the stellar parameters and abundances obtained from the Bayesian analysis. The good agreement across multiple ions demonstrates the consistency of the inferred parameters and the robustness of the global fitting approach. The horizontal axis is given in pixel number rather than wavelength; the corresponding spectral ranges are indicated by the panel labels. The names identifying the sub-panels are orientative only: each panel may include several spectral features, and the label marks approximately the central wavelength of the region shown.