how to set styles for style classes in react js code example

Example 1: Styling React Using CSS

class MyHeader extends React.Component {
  render() {
    return (
      <div>
      <h1 style={{color: "red"}}>Hello Style!</h1>
      <p>Add a little style!</p>
      </div>
    );
  }
}

Example 2: use styles in react

const useStyles = makeStyles(theme => ({
  textField: {
    marginLeft: theme.spacing(1),
    marginRight: theme.spacing(1),
    border: '1px solid red',
  },
}));
function App() {
  const classes = useStyles();
return (
    <TextField
      id="outlined-name"
      label="Name"
      className={classes.textField}
      margin="normal"
      variant="outlined"
    />
  );
}