  Jets can become collimated as they propagate through dense environments and
understanding such interactions is crucial for linking physical models of the
environments to observations. In this work, we use 3D special-relativistic
simulations to study how jets propagate through the environment created around
a neutron star merger remnant by neutrino-driven winds. We simulate four jets
with two different initial structures, top-hat and Gaussian, and two
luminosities. After jet breakout, we study the angular jet structures and the
resulting afterglow light curves. We find that the initial angular structures
are efficiently washed out during the propagation, despite the small wind mass
of only $\sim 10^{-3}$ M$_\odot$. The final structure depends on the jet
luminosity as less energetic jets are more strongly collimated, and entrainment
of baryons leads to a moderate outflow Lorentz factor ($\approx 40$). Although
our jets are not specifically intended to model the outflows of the GW170817
event, we show that they can be used to produce light curves consistent with
the afterglow observed in the aftermath of GW170817. Using this procedure we
show how the inferred physical parameters e.g., inclination angle, ambient
particle number density, can vary substantially between independent fits of the
same dataset and appear to be sensitive to smaller details of the angular jet
shape, indicating that observationally inferred parameters may depend
sensitively on the employed jet models.
