function main() {
  const hud=$env.mode==='hud';
  const r=$data.current;
  return <CardContent title={hud?'HUD 速度':'速度'}>
    <VStack spacing={6}>
      <Text fontSize={hud?72:58} fontWeight={hud?'semibold':'light'}
        minimumScaleFactor={0.5} color={HDR($env.foreground)}>
        {r.speed===null?'—':Math.round(r.speed)}
      </Text>
      <Text fontSize={12} color={HDR($env.accent)}>{r.speedUnit}</Text>
    </VStack>
  </CardContent>;
}