Resubmission Soft Rejection (IFrame Buster Help)

I have published tons of products here on Envato with no problem.
This is my first time i ever encounter 3 resubmission soft rejections back to back.

Here is my problem from the reviewer:
Envato displays items for sale inside an iframe (with a buy button at the top). Sometimes items may not work or display when framed. In cases like this it is recommended to add a framebuster to your item demo page. You can google iframe buster to add this simple script to the top of your demo page.

When i google “Iframe buster” I seem to cant find the solution to this issue. Besides this customer Themeforest Preview Bar:

I am lost…