Neumorphism

The recipe is short and unusually exact, which is part of why the style spread so fast. Everything on screen is one background colour, the controls included. Each control gets two shadows, a light one up and to the left and a dark one down and to the right, as though a single soft lamp sits off the top left corner. There are no borders, and no fill that differs from the background. Get those right and a button appears to have been pushed up out of the surface rather than placed on it. Generators such as neumorphism.io exist because the numbers are the whole craft: the two shadows have to be tints of the base colour, and a hard edge or a saturated shadow breaks the illusion immediately.

The style has exactly one state change, and it is the same trick with the sign flipped. Pressing a control moves both shadows inside it, so the light now falls into the top left of a hollow and the dark pools at the bottom right, and the shape reads as pressed into the surface instead of raised out of it. Extruded and debossed are the two poles the whole vocabulary is built from: a switch is a carved track with a raised knob, a dial is a raised disc in a carved well. Nothing else about the control moves.

Then the problem the style cannot design its way around. With no border and no fill of its own, a control differs from its background by a few percent of luminance in two thin gradients. Its contrast ratio against the surface behind it is essentially 1:1, where WCAG asks for 3:1 on the boundary of any control you are meant to find (see non-text contrast). It fails in bright sunlight, on a cheap panel, at a tilted viewing angle, and for anyone with reduced contrast sensitivity, and unlike most contrast failures it cannot be fixed by adjusting a value, because the sameness is the aesthetic. Disabled and focus states have nowhere to go either, since the only two appearances are already spent on raised and pressed.

That is why it peaked around 2020 and mostly stayed in portfolio shots, calculators and music players rather than in products with real content. The tactile idea did survive, in relatives that kept the softness and gave up the sameness. Claymorphism inflates a pastel solid that is clearly not the background. Neo-skeuomorphism depicts distinct materials at real contrast, so the button is visibly a different substance from the panel. Deformable UI takes the softness into behaviour, where a control squashes under a finger rather than merely inverting a shadow. Sorting them by material is the fastest way to keep the words apart: glass is translucent, clay is puffy and pastel, and neumorphism is the same colour as the thing it sits on.