old_contents: import React from 'react';
  import PropTypes from 'prop-types';
  import { withStyles, Fab } from '@material-ui/core';
  
  const styles = theme => ({
    FAButton: {
      position: 'absolute',
      top: -28,
      left: theme.spacing.unit * -6,
      // Para o botão ficar por cima das imagens do Card
      zIndex: theme.zIndex.mobileStepper,
    },
    [theme.breakpoints.down(1000 + theme.spacing.unit * 8)]: {
      FAButton: {
        position: 'fixed',
        top: 'auto',
        left: 'auto',
        bottom: 20,
        right: 20,
      },
    },
  });
  
  const FAButton = ({ children, classes, onClick, ...rest }) => (
    <Fab onClick={onClick} color="secondary" className={classes.FAButton} {...rest}>
      {children}
    </Fab>
  );
  
  FAButton.propTypes = {
    children: PropTypes.node.isRequired,
  };
  
  export default withStyles(styles)(FAButton);
  
new_contents: import React from 'react';
  import PropTypes from 'prop-types';
  import { withStyles, Fab } from '@material-ui/core';
  
  const styles = theme => ({
    FAButton: {
      position: 'fixed',
      top: 'auto',
      left: 'auto',
      bottom: 23,
      right: 23,
      // Para o botão ficar por cima das imagens do Card
      zIndex: theme.zIndex.mobileStepper,
    },
  });
  
  const FAButton = ({ children, classes, onClick, ...rest }) => (
    <Fab onClick={onClick} color="secondary" className={classes.FAButton} {...rest}>
      {children}
    </Fab>
  );
  
  FAButton.propTypes = {
    children: PropTypes.node.isRequired,
  };
  
  export default withStyles(styles)(FAButton);
  
subject: Fix FAButton to the bottom for all screen sizes