<Box sx={{ flexGrow: 1 }}>
  <SparkLineChart data={[3, -10, -2, 5, 7, -2, 4, 6]} height={100} area />
</Box>
<Box sx={{ flexGrow: 1 }}>
  <SparkLineChart
    data={[3, -10, -2, 5, 7, -2, 4, 6]}
    height={100}
    curve="natural"
    area
  />
</Box>