Thanks for your advice.
For now, I chose the option of "Resize iframe to content height" and set the height to "10,000px" so that the scroll bar is not displayed in most of the cases on big screens.
The above setting also allows mobile users to use their two fingers to scroll.
So should I stick to my tweak or do you believe I should stick to your suggestion?
I am new to CSS, so i believe I will need to do some googling to figure out the detection on mobile devices.
By the way, I have a major problem as to forcing iFrame content displayed on its wordpress parent page.
As you may be aware I have iframed several of my subsites. (You can have a look at http://www.koreaobserver.com)
Now I want people directly accessing to my subsites through google or other search engines automatically redirected to the parent site where the corresponding subsites are shown in an iframe.
There is a wordpress plugin called "force-frame," which "allows you to force your WordPress website inside an iframe in another website, with cross-domain support."
The plugin is supposed to do what I desire if it works. Nevertheless, i don't understand the plugin's installation instruction, which says "Add the following snippet inside the HTML of the parent."
HTML of the parent? I have no clue as to the html of the parent.
Do you have any suggestion on that?