how to use styles in material ui code example

Example 1: material ui common styles

const useStyles = makeStyles({
  root: {
    color: 'red',
    '& p': {
      color: 'green',
      '& span': {
        color: 'blue'
      }
    }
  },
});

Example 2: create a common style material ui style

const styles = theme => ({
  ...card(theme),
  grid: {
    height: '100%',
    width: 'fit-content',
    paddingLeft: theme.spacing.unit * 2,
    paddingRight: theme.spacing.unit * 2,
    flexWrap: 'nowrap',
    overflowY: 'hidden',
  },
  name: {
    overflow: 'hidden',
    textOverflow: 'ellipsis',
    fontSize: '1.12rem',
    fontColor: theme.palette.text.main,
    [theme.breakpoints.down('sm')]: {
      fontSize: '0.9rem',
    }
  },
  state: {
    textOverflow: 'ellipsis',
    margin: '0 auto',
    marginTop: theme.spacing.unit / 2,
    fontSize: '1.0rem',
    fontColor: theme.palette.text.light,
    [theme.breakpoints.down('sm')]: {
      fontSize: '0.8rem',
    }
  },
  alarmArmedHome: {
    background: theme.palette.backgrounds.card.alarm.home,
  },
  alarmArmedAway: {
    background: theme.palette.backgrounds.card.alarm.away,
  },
  alarmTriggered: {
    background: theme.palette.backgrounds.card.alarm.triggered,
  },
  icon: {
    margin: '0 auto',
    color: theme.palette.text.icon,
    fontSize: '2.7rem',
    [theme.breakpoints.down('sm')]: {
      fontSize: '1.7rem',
    }
  },
});