How to remove iframe's scrollbars?

Question

How to remove iframe\'s scrllbars? In Firefox it\'s easy, however I found myself unable to achieve this effect to be compatible with all major browsers.

Answer 1

on top of Alex's answer, I also had to add the following to remove horizontal toolbars from both FF and Chrome. This was added in the i-frame page, even though it should be possible to add it in the css as well: