message: tidy up HTML, point at dist/css/build.css
diff: -const css = require('../src/css')
  -
  -module.exports = ({html = '', scripts, title = 'primer-react', static: staticBuild}) =>
  +module.exports = ({html = '', scripts, title = 'primer-react', basename, static: staticBuild}) =>
  `<!DOCTYPE html>
  <html>
  <head>
  <title>${title}</title>
  - <meta name='viewport' content='width=device-width,initial-scale=1' />
  - <meta name='generator' content='Compositor X0' />
  - <meta name='og:title' content='Primer React' />
  - <meta name='description' content='Primer components built with React.js.' />
  - <link rel='icon' href='/assets/favicon.png' />
  - <style id="primer-css">${css}</style>
  + <meta name='viewport' content='width=device-width,initial-scale=1'>
  + <meta name='generator' content='Compositor X0'>
  + <meta name='og:title' content='Primer React'>
  + <meta name='description' content='Primer components built with React.js.'>
  + <link rel='icon' href='https://primer.github.io/favicon.png'>
  + <link rel='stylesheet' href='${basename}/dist/css/build.css'>
  </head>
  <body>
  <script>
  