message: style <details> reset w/Emotion
diff: import React from 'react'
  import PropTypes from 'prop-types'
  import classnames from 'classnames'
  +import styled from 'react-emotion'
  import {withSystemProps, COMMON, withoutPropTypes} from './system-props'
  +const DetailsReset = styled('details')`
  + & > summary { list-style: none; }
  + & > summary::before { display: none; }
  + & > summary::-webkit-details-marker { display: none; }
  +`
  +
  class Details extends React.Component {
  constructor(props) {
  super(props)
  @@ -10,7 +17,7 @@ class Details extends React.Component {
  this.toggle = this.toggle.bind(this)
  }
  - toggle(event) {
  + toggle = event => {
  if (event) {
  event.preventDefault()
  }
  @@ -18,13 +25,13 @@ class Details extends React.Component {
  }
  render() {
  - const {className, children, render = getRenderer(children), ...rest} = this.props
  + const {children, render = getRenderer(children), ...rest} = this.props
  const {open} = this.state
  return (
  - <details {...rest} className={classnames('details-reset', className)} open={open}>
  + <DetailsReset {...rest} open={open}>
  {render({open, toggle: this.toggle})}
  - </details>
  + </DetailsReset>
  )
  }
  }
  