message: fix array-like margin
  in mui-beta.22 jss-expand plugin was removed, so previous syntax doesn't work anymore
diff: @@ -121,7 +121,7 @@ const styles = theme => ({
  display: 'flex',
  justifyContent: 'center',
  alignItems: 'flex-end',
  - margin: [theme.spacing.unit * 4, 0, theme.spacing.unit],
  + margin: [[theme.spacing.unit * 4, 0, theme.spacing.unit]],
  },
  clock: {
  backgroundColor: 'rgba(0,0,0,.07)',
  