how to use css in material ui

1<Button
2  classes={{
3    root: classes.root, // class name, e.g. `classes-nesting-root-x`
4    label: classes.label, // class name, e.g. `classes-nesting-label-x`
5  }}
6>
7  classes nesting
8</Button>

1import React from 'react';
2import Button from '@material-ui/core/Button';
3import './PlainCssButton.css';
4
5export default function PlainCssButton() {
6  return (
7    <div>
8      <Button>Default</Button>
9      <Button className="button">Customized</Button>
10    </div>
11  );
12}