The scene it sits on
A shadow is just darkness added to whatever is behind it. Slide the background down toward black and watch it disappear.
The CSS
Realistic elevation
Five heights, each built from three layers: a tight one that draws the edge, a middle one, and a wide faint one pulled in with negative spread. Higher up means softer and further, not darker.
Or start from a feel
Layer stack
Six layers is the limit here — remove one to add another. Real stacks rarely need more than four.
The first layer in the list paints on top. Each row shows that layer on its own — the trick is that none of them look like much alone.
Editing layer 1
This layer is switched off, so nothing you change here shows up yet. Flip it back on in the stack above.