Best way to use fullheight/-width iframes

I have a usecase where I need to insert an iframe within my app. That iframe should be shown as a “normal” page in the app. Currently I’m using

<iframe seamless src="" style="width: 100%; min-height: 100%;">

But that causes double vertical scrollbars (one for the iframe and one from the app itself).
Is there a better way to do that? Maybe to get the height from the iframe content and make the iframe exactly that height instead of 100%?

No one?
Is this the intended way to use iframes?

IFrames are…painful. You’d have to hide the scrollbars with CSS, though I haven’t worked much with how iFrames work in mobile situations. Support for iframes and scrollbars is pretty wonky, this isn’t really a mobile app kind of question its a general web dev question. Search a bit and you’ll see how with HTML5 the iframe has various challenges with scrollbars.