gatsby-ssr.js

exports.onPreRenderHTML = ({ getHeadComponents, replaceHeadComponents }) => {
  if (process.env.NODE_ENV !== 'production') return

  getHeadComponents().forEach(el => {
    if (el.type === 'style') {
      el.type = 'link'
      el.props.href = el.props['data-href']
      el.props.rel = 'stylesheet'
      el.props.type = 'text/css'

      delete el.props['data-href']
      delete el.props.dangerouslySetInnerHTML
    }
  })
}