Elevation, and why it does not work in the dark
Two shadows per level, distance doubling — and a dark preview showing why a shadow scale does nothing there.
Elevation, and why it does not work in the dark
Each level is two shadows — a tight contact one and a wide ambient one — with the distance doubling per level. On a dark surface none of it is visible, and that is worth saying out loud.
Two shadows per level
Real light produces a tight, dark contact shadow where an object meets a surface and a much broader, softer ambient one further out. A single blur can be one or the other.
Distance doubles per level, which is what makes the steps read as distinct heights rather than as slightly different blurs. Opacity falls slightly as the level rises, because a higher object casts a more diffuse shadow.
None of this works on a dark surface. A shadow is a darkening, and there is nothing left to darken. Dark themes carry elevation with a lighter surface colour instead — the higher the element, the lighter its background — and a shadow scale reused there does nothing at all.
Elevation should mean something
If every card has a shadow, the shadow says nothing. Elevation is a signal about what is above what — a menu over a page, a modal over everything — and using it decoratively spends the signal.
Shadows are expensive
Large blurs are costly to paint and the cost grows with the radius and the area. A list of a hundred cards each with a four-layer shadow is a common cause of scroll jank; one layer, or a border, is usually enough at that scale.