alt Hacker NewsI'm sorry but that's just slop. The elevation in the actual CSS makes the shadow progressively lighter (technically correct, thought the proportions look very wrong, 2 is too dark), while the 3D model has it constant. There is nothing in this 'camera and lighting setup' that was translated to the styles.
The threejs scene in the docs is only for explaining the setup; it doesn't have a raytracer to render shadows accurately. The reference renders for the CSS were done in Blender. See https://kikkupico.github.io/ambientcss/ambient-css/grounded#... for examples.