You have to give an iframe a specific height in pixels. There is no “make this iframe the height its content wants to be (like normal HTML).
This leads to two options:
- your page has nested vertical scroll bars (awful UX)
- you have to write JavaScript inside and outside the frame to constantly measure and communicate how tall the frame wants to be.
I guess, the best you could do is emulating a frameset layout with a fixed navigation and a display frame for the actual content. (By setting the overflow to `hidden` you can get rid of the outer scrollbars.)
(Of course, this has all the issues of framesets, as in deep linking, accessibility, etc.)