correctly set page length when including content from an external domain in our pages

We have been using use iframes to include external content in pages that have our look and feel. This causes a problem because we need to determine the page length. The iframe does not know the length when the content is from an external domain. also, the page length needs to adjust when the external content changes length. I understand there is jquery code to help with the iframe. we are open to other ideas. We do not want scroll bars on the page or in the frame.