old_contents: import React, { PropTypes } from 'react'
  import { connect } from 'react-redux'
  import { Row, Col } from 'react-flexbox-grid'
  import setPropTypes from 'recompose/setPropTypes'
  import compose from 'recompose/compose'
  
  const Log = compose(
    connect((state) => ({ log: state.log })),
    setPropTypes({
      log: PropTypes.array.isRequired
    })
  )(({ log }) => (
    <Row>
      <Col>
        {
          log.map((content, idx) => (
            <Row key={ idx }>
              <Col> { content } </Col>
            </Row>
          ))
        }
      </Col>
    </Row>
  ))
  
  export default Log
  
new_contents: import React, { PropTypes } from 'react'
  import { connect } from 'react-redux'
  import { Row, Col } from 'react-flexbox-grid'
  import setPropTypes from 'recompose/setPropTypes'
  import compose from 'recompose/compose'
  
  const Log = compose(
    connect((state) => ({ log: state.log })),
    setPropTypes({
      log: PropTypes.array.isRequired
    })
  )(({ log }) => (
    <Row>
      <Col style={ styles.scroll }>
        {
          log.map((content, idx) => (
            <Row key={ idx }>
              <Col> { content } </Col>
            </Row>
          ))
        }
      </Col>
    </Row>
  ))
  
  const styles = {
    scroll: {
      width: '25%',
      height: '600px',
      overflow: 'auto',
      padding: '0 10px'
    }
  }
  
  export default Log
  
subject: Update style