Mean Euclid Q1 quasar composite spectra constructed with different rest-frame wavelength bin sizes. The three curves show mean composites built on grids with Δλ = 4.0 Å (blue), 8.0 Å (orange), and 13.4 Å (green). For clarity, the spectra are vertically offset by multiplicative factors, as indicated on the right-hand side. The top panel displays the optical range (300–700 nm) and the bottom panel shows the near-infrared range (700–1400 nm). The continua of the three spectra show close agreement, while the two spectra with larger bin sizes have flattened emission line peaks.