I enclosed some screenshots with more details. In order to see the full mark I had to right and click edit after selecting the chart or click copy inner html and paste to text editor. The id and class attribute are unquoted in raw markup as show screenshot bellow. I also verified the browser and doc mode are set correct as indicated in screenshot bellow. Hope this helps a little more. If look at it just in the dom view in the developer bar it never shows the issue cause it formats everything.