* introduce "pill" to be explicit about fully rounded, vs a "None" radius
* no-op transition to CornerRadii
* popup button to spec
* restore "fully rounded" layout behavior
* use plain light to better show highlight
* persistent split to spec (for day theme anyway)
* remove night-theme colors for speed panel
* fixup docs for pill
* CR: remove unnecessary `row`
* CR: remove outdated doc
* import order
