Close-up view of the wind diagnostic lines in the STIS and FOS spectra, as well as Hα, which is part of the X-Shooter (2020) spectrum. The observed spectrum is shown in blue and needs to be compared to the combined synthetic spectrum, shown in red. In the combined synthetic spectrum ISM absorption lines, which originate from the Galactic foreground and in the SMC, are included and labeled as “(is)”. For the STIS and FOS spectrum we plot the weighted synthetic spectra. For the X-Shooter (2020) spectrum we show the unweighted synthetic spectra of the primary and the secondary as black dotted and green dotted lines, respectively. A close-up view of the He IIλ4686 wind diagnostic line can be found in Fig. D.1.