Iframe in full page

Hi, thank YOU for the great CMS!
I'm using the default theme. On one page, I want to include an iframe that takes the exact full size available in the window for the <div class="content">.
The iframe is <iframe src="https://webchat.botframework.com/embed/bot" width="100%" height="100%"></iframe>, but the height="100%" does not fill the window.

Does anyone have guidance please?
I feel like I need to create a specific page template and play with the javascript size calculations, or with the vh size units...
Thanks

The iFrame really needs some boundaries in order to know how high to be. If you don't have something that provides that height, then it has no clue what 100% is. 100% of what? It doesn't know how high the internal content is going to be until it's rendered. This might help: http://stackoverflow.com/questions/325273/make-iframe-to-fit-100-of-containers-remaining-height