_prepareHtml (html, options) {
    const { header, footer } = options
    const appendHeaderFooter = !!header || !!footer
    if (!appendHeaderFooter) {
      return createMarkdownArticle(html)
    }

    if (!options.extraCss) {
      options.extraCss = footerHeaderCss
    } else {
      options.extraCss = footerHeaderCss + options.extraCss
    }

    let output = HF_TABLE_START
    if (header) {
      output += createTableHeader(options)
    }

    if (footer) {
      output += HF_TABLE_FOOTER
      output = createRealFooter(options) + output
    }

    output = output + createTableBody(html) + HF_TABLE_END
    return sanitize(output, EXPORT_DOMPURIFY_CONFIG, false)
  }
@private

@param {string} html The converted HTML text.
@param {*} options The export options.