Long shadow

Long shadow was the compromise the flat era made with itself. Flat design had just thrown out every bevel and gloss that skeuomorphism relied on, and the icons that came out the other side were legible but inert. A single hard shadow, thrown down and to the right at 45 degrees and running two or three times the width of the shape, gave a mark somewhere to sit without pretending anything was made of glass or leather. It was decoration that admitted it was decoration, which is why it dated so precisely: an icon with one still reads as 2013 the way a drop cap reads as a manuscript.

The rules were strict, and the strictness is what made it a style rather than a shadow. One light source for every icon in the set, always upper left, so every shadow ran the same way. No blur at all, because a soft edge belongs to a shadow cast by something real and this one is a graphic. A colour taken from the tile rather than from black, so the trail reads as a darker patch of the same surface instead of a smudge over it. And a finite length: the shadow either fades to the tile colour or is cut clean by the tile’s edge, which is the difference between a long shadow and a shape that has simply been extruded.

It went out of fashion for a reason worth remembering. The trail is the largest thing in the tile, so it fights the glyph it is supposed to support, and at small sizes the two merge into a diagonal smear where the icon should be. Material Design’s arrival replaced the effect with elevation that behaves consistently, and a shadow that means a height survived while a shadow that meant style did not. The technique is still useful for display type, key art, and anything deliberately dated, and it is worth knowing by name so a team can say what era a proposed icon set is quoting.