Topmost panel: Stacked spectrum of a SFR–M_⋆ bin (M_⋆ = 10^8.65 M_⊙ and SFR = 1^−1.3 M_⊙ yr⁻¹), showing zoomed-in views of the spectral fits around some of the strong nebular lines. In the subplots below we zoom in on the fit residuals in specific spectral regions to highlight the detection of faint, temperature-sensitive auroral lines (in red) and other nearby emission lines (blue). The dashed green lines represent the standard deviation of residual fits in each wavelength window. The emission line fluxes and associated uncertainties, global and radially binned, are available online (see Tables B.3 and B.4).