Another example of where I use Iframes is on this premade layouts page! I use it on the changelog so I don't have to update it on every page of this site, the only page that needs updating is this one.
Here is the code:
as you can see, this is not just a scroll box div element but instead a whole seperate page being displayed within an Iframe that scrolls.
the code we used to display the test page is:
<iframe src="https://pomelo.neocities.org/premades/tutorials/iframes/testpage.html" height="200" width="600"style="border: none;"></iframe>
Feel free to experiment with linking pages on your site this way, it allows for faster loading, seperate css and not disturbing things like gifs, music players, videos and just makes your site all around cooler in my opinion!