Theoretical linear growth rate as a function of the horizontal wavenumber in the presence of a magnetic field (θ = 10°). The black curves indicate the asymptotic limits corresponding to the fully uncoupled and fully coupled regimes. The colored curves show intermediate coupling cases for two different assumptions on the variation of the collision frequency across the interface. The dashed bands mark the ranges of wavelengths injected in the simulations, illustrating how the numerical experiments sample the different coupling regimes predicted by linear theory.