Animations of dwarf galaxies from the RT simulation at z=4. Purple/yellow points are stars, the red surface is the isosurface of metallicity Z = 0.025 solar, the greenish surface is the isosurface of x(HI) = 0.1. The edge of the HI disk is very sharp, and isosurfaces of x(HI) = 0.03 or x(HI) = 0.3 almost coincide with x(HI) = 0.1, but there is a strong metallicity gradient in the HI disk: the isosurface of Z = 0.01 solar would cover almost all HI disk, the isosurface of Z = 0.1 is well inside the stellar disk.