Opaque spring configuration. Construct one via a preset (gentle, wobbly, stiff, slow, noWobble) or custom.

Pass to whichever animation or scroll engine accepts a spring; the engine will run the motion until the value is settled. There is no explicit duration — the spring's stiffness, damping, and mass determine how long it takes to come to rest.

A soft, slow settle. Mild overshoot, takes its time.

Good for: hero-element reveals, large modals, anything where a sense of weight is welcome.

Lively and bouncy. Several visible oscillations before settling.

Good for: playful UI accents, attention-grabbing reveals, cartoony interactions.

Snappy and direct. Small overshoot, settles quickly.

Good for: button presses, tooltip reveals, anything that should feel crisp and immediate.

Low stiffness with extra damping — a long, mellow approach.

Good for: ambient motion, slow-developing reveals, "drifting into place" effects.

Critically damped — the fastest approach to the target with no overshoot whatsoever.

Good for: when you want spring-like timing but tween-like absence of overshoot. Useful for scroll handoffs and other places where bounce would look like a bug.

Hand-tune a spring's physics.

• stiffness — how strongly the spring pulls toward the target. Higher is snappier, lower is loose. Typical 100..400. (Hooke's-law. Must be >= 0.)
• damping — how much friction slows the motion. Higher is less wobbly, lower is bouncier. Typical 10..40. (Viscous friction. Must be >= 0.)
• mass — how heavy the thing feels. Heavier is more sluggish, lighter is more reactive. Typical 1.0. Must be > 0.

If you want to dial in a specific feel, the ratio damping / (2·√(stiffness·mass)) controls the overall character:

• less than 1 — bouncy: overshoots and oscillates before settling
• exactly 1 — crisp: fastest possible settle with no overshoot
• more than 1 — sluggish: eases in slowly without overshoot

Inputs are clamped: stiffness and damping below 0 become 0, mass below 1e-6 becomes 1e-6.

customSpring : Spring
customSpring =
    Motion.Spring.custom
        { stiffness = 220
        , damping = 16
        , mass = 1
        }