message: use StyleProvider in examples/_app.js
diff: import React from 'react'
  import PropTypes from 'prop-types'
  import {NavLink} from 'react-router-dom'
  -import Styles from './doc-components/Styles'
  import Octicon, {Package} from '@githubprimer/octicons-react'
  -import {Block, Link, Text, UnderlineNav} from '../src'
  +import {Block, Link, StyleProvider, Text, UnderlineNav} from '../src'
  import {name, repository, version} from '../package.json'
  const pkg = `${name}@${version}`
  @@ -12,7 +11,7 @@ const releaseURL = `https://github.com/${repository}/releases/v${version}`
  export default function Page({render}) {
  return (
  <React.Fragment>
  - <Styles />
  + <StyleProvider />
  <div className="text-dark-gray">
  <UnderlineNav
  actions={
  