I think the error in the Chrome Dev Tools console is very helpful:
code.jquery.com/jquery-2.2.4.min.js:4 Mixed Content: The page at 'https://codepen.io/' was loaded over HTTPS, but requested an insecure script 'http://api.forismatic.com/api/1.0/?jsonp=...'. This request has been blocked; the content must be served over HTTPS.