Design kit

The body face is the system stack, so text renders natively at any size without a second download. Only the display face is fetched, because it sets the first thing anyone reads and the fallback for it is visibly wrong.

This paragraph exists to run past a single line, so line height, measure and the gap between paragraphs can be judged against each other rather than guessed at. A design system that has only ever been tested on short strings has not been tested. A link sits inside running text and has to stay legible without shouting; a fragment of code has to sit on the same baseline as the words around it.

• An unordered list, for things with no order
• A second entry, longer than the first, so the indent and the wrap can both be seen at once
• A third

A quotation, which is the one place the page speaks in a voice that is not its own and should look like it.

The background is not one setting. What is drawn behind the page and what that does over time are different questions, and answering them with one control is what forces a design system to ship a still copy of every pattern it owns. Here they are separate: pick any appearance, then pick how alive it is, and the two do not know about each other.

• Appearance is the pattern alone. Each one reads the palette, so none of them carries a colour that can clash with the one you chose.
• Animation is three behaviours - its own clock, the scrollbar, and the pointer - named as five levels. They reach the stylesheets as multipliers, which is why Still needs no separate stylesheet: every distance is multiplied by nothing.
• Intensity is amplitude, not a second switch. It scales how far the movement goes and how quickly, and at Still it changes nothing at all.
• Scroll is the one behaviour that has a direction. Sink sends the pattern down against the text, Lift carries it up with the text but slower, and the two dials beside it set how far all of it travels and how much the near depths outrun the far ones. At no separation they travel together and the depth collapses to a single plane.
• Pointer is how the pattern acknowledges the cursor: a soft colour shift where it rests, and at the top level a slow wave from the same spot. Nothing chases it. Reactive is the separate case where the scene itself eases out of the pointer's way.

Every appearance answers the scrollbar, each depth by its own amount, and two of them are built around it: Tiers and Haze draw horizontal ranks that separate as the page moves, and can travel much further than the rest because a pattern that repeats along the page has no edge to run out of. Some appearances have more behind them than a gradient. Parallax draws a chosen set of line art at four depths, panning sideways on its own clock and sliding vertically with the scroll; the art is a mask, so the palette colours it and a whole set costs one stylesheet and no extra request. Particles, Code and Bench are one machine wearing three finishes - a field of drifting marks with a spring under each one, pushed aside by the pointer and settling back. Nothing here loads a framework, and the only scripts involved write numbers.