Aqua

Aqua arrived with Mac OS X in 2000 and made water the governing metaphor of a desktop. Buttons were rounded capsules filled with a saturated blue and glazed like sweets, which is where the nicknames gel, candy, and gumdrop all come from. Steve Jobs introduced them by saying they looked so good you would want to lick them, and the press ran with it for a decade. Windows carried a soft drop shadow and a translucent title bar, the close, minimise and zoom controls became three coloured lozenges at the top left, scrollbars were blue glass capsules in a recessed trough, and backgrounds were ruled with fine white pinstripes borrowed from shirting. The default button in a dialog did not merely sit there: it pulsed, brightening and dimming about once a second, so the safest way forward announced itself without a word.

The gloss is a stack of four things and no more. A saturated core colour, a specular highlight across the upper half that fades to nothing by the middle, a soft inner glow near the bottom edge where light bounces back up through the body, and a thin dark rim to keep the shape from dissolving into the window. Change the rim and you get plastic; drop the lower glow and you get a flat gradient. Depth was hierarchy: the button carrying the recommended action was the only blue one in a row of grey ones, so weight, colour, and that slow pulse all pointed the same way. The style was not shy about cost either, since every one of those surfaces was drawn per control rather than reused as a token.

Aqua is the best documented member of the skeuomorphism family, and the one that shows the arc most clearly. The glaze thickened for a decade, reaching leather stitching and torn paper in Apple’s own applications, then reversed hard in 2013 when iOS 7 stripped the ornament out in a single release and the rest of the industry followed into flat design. What came back in 2025 was not gloss but transparency: Liquid Glass refracts and bends whatever sits behind a control instead of pretending the control is made of candy, which is the same instinct rendered by a machine that can afford real optics.

As a register today it reads as period costume, which is a legitimate thing to want. It suits work about the early 2000s, retro utilities, and interfaces that are deliberately playful, and it is very good at making a single primary action unmistakable. Two cautions. Gloss applied to everything erases the hierarchy it was invented to create, so if every control shines then nothing is the default. And the pulse is a real accessibility problem by modern standards: a looping brightness change near text should honour a reduced motion preference, which is exactly the sort of thing a 2000s desktop had no vocabulary for.