http://us5.campaign-archive1.com/?u=ea228d7061e8bbfa8639666ad&id=b28be5f58a&e=313c7b398a

http://www.html5rocks.com/en/tutorials/security/sandboxed-iframes/

http://caniuse.com/#feat=iframe-sandbox

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe

Also allow attributes and stuff. See CodePen.