  We present first realistic numerical simulations of 3D radiative convection
in the surface layers of main sequence A-type stars with Teff = 8000 K and 8500
K, log g = 4.4 and 4.0, recently performed with the CO5BOLD radiation
hydrodynamics code. The resulting models are used to investigate the structure
of the H+HeI and the HeII convection zones in comparison with the predictions
of local and non-local convection theories, and to determine the amount of
"overshoot" into the stable layers below the HeII convection zone. The
simulations also predict how the topology of the photospheric granulation
pattern changes from solar to A-type star convection. The influence of the
photospheric temperature fluctuations and velocity fields on the shape of
spectral lines is demonstrated by computing synthetic line profiles and line
bisectors for some representative examples, allowing us to confront the 3D
model results with observations.
