text: import React from 'react';
  import PropTypes from 'prop-types';
  import classNames from 'classnames';
  import withStyles from '../styles/withStyles';
  import { capitalize } from '../utils/helpers';
  
  export const styles = theme => ({
    /* Styles applied to the root element. */
    root: {
      position: 'absolute',
      height: 2,
      bottom: 0,
      width: '100%',
      transition: theme.transitions.create(),
      willChange: 'left, width',
    },
    /* Styles applied to the root element if `color="primary"`. */
    colorPrimary: {
      backgroundColor: theme.palette.primary.main,
    },
    /* Styles applied to the root element if `color="secondary"`. */
    colorSecondary: {
      backgroundColor: theme.palette.secondary.main,
    },
  });
  
  /**
   * @ignore - internal component.
   */
  function TabIndicator(props) {
    const { classes, className, color, ...other } = props;
  
    return (
      <span
        className={classNames(classes.root, classes[`color${capitalize(color)}`], className)}
        {...other}
      />
    );
  }
  
  TabIndicator.propTypes = {
    /**
     * Override or extend the styles applied to the component.
     * See [CSS API](#css-api) below for more details.
     */
    classes: PropTypes.object.isRequired,
    /**
     * @ignore
     */
    className: PropTypes.string,
    /**
     * @ignore
     * The color of the tab indicator.
     */
    color: PropTypes.oneOf(['primary', 'secondary']),
  };
  
  export default withStyles(styles, { name: 'MuiTabIndicator' })(TabIndicator);
  