如何覆盖material-ui-next中浮动标签文本和下划线颜色的TextField？

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

const styles = {
  root: {
    '& .MuiInputLabel-root': {
      color: 'red', // 设置浮动标签文本的颜色
    },
    '& .MuiInput-underline:before': {
      borderBottomColor: 'green', // 设置下划线的颜色
    },
  },
};

function CustomTextField(props) {
  const { classes } = props;

  return (
    <TextField
      {...props}
      className={classes.root}
    />
  );
}

export default withStyles(styles)(CustomTextField);

<CustomTextField
  label="Custom TextField"
  variant="outlined"
/>