如何使用Material-UIv1.0.0-beta.30中的内置网格让粘性页脚工作？

npm install @material-ui/core@1.0.0-beta.30

yarn add @material-ui/core@1.0.0-beta.30

import React from 'react';
import { Grid, Paper } from '@material-ui/core';
import { withStyles } from '@material-ui/core/styles';

const styles = theme => ({
  root: {
    flexGrow: 1,
    minHeight: '100vh',
  },
  paper: {
    padding: theme.spacing.unit * 2,
    textAlign: 'center',
    color: theme.palette.text.secondary,
  },
  footer: {
    marginTop: 'auto',
    backgroundColor: theme.palette.background.paper,
    padding: theme.spacing.unit * 2,
  },
});

class App extends React.Component {
  render() {
    const { classes } = this.props;

    return (
      <div className={classes.root}>
        <Grid container spacing={24}>
          <Grid item xs={12}>
            <Paper className={classes.paper}>Content</Paper>
          </Grid>
        </Grid>
        <footer className={classes.footer}>
          <Paper className={classes.paper}>Sticky Footer</Paper>
        </footer>
      </div>
    );
  }
}

export default withStyles(styles)(App);