Button press
A press is the interface saying it heard you. It is the most frequent piece of feedback in a product and it should be nearly invisible.
`transform: scale(0.96)` on `:active`, with a 100–160ms transition on transform. Scale takes the label and the icon with it, which is what makes it read as a physical press rather than a colour change. Below 0.95 feels exaggerated. `:active` is a real press on touch, so no hover gating is needed here; hover styling is gated separately.
- scale(0.96), never below 0.95
- 100–160ms, ease-out, as a transition not a keyframe
- Static cue as well: a pressed control also changes surface or ink, so the feedback survives without motion