title: Chinese and Japanese character encoding issues when exporting HTML to PDF
body: <p>I run a web-based timeline maker that lets users create timelines in HTML/JavaScript and then export them to PDF files for printing when they're done.</p>
  
  <p>I have had several users report issues with exporting their timelines to PDFs when the timelines contain certain Unicode characters. Here, for example, is a screenshot showing the web page and the PDF file that is generated:</p>
  
  <p><img src="https://i.stack.imgur.com/6NSe0.png" alt="enter image description here"></p>
  
  <p>I've been trying to wrap my head around why some Unicode character blocks like Block Elements and Georgian will export but Chinese and Japanese will not. Also, the export works correctly when I perform it on my local computer, but results in the above output when exporting on Heroku.</p>
  
  <p>Does anyone know what might be causing this?</p>
  
  <p>For completeness, the backend is in Ruby on Rails and it uses the PDFKit gem to convert the HTML page to a PDF and the site is hosted on Heroku.</p>