Handling resize is a different beast than being responsive. Working for every viewport dimension under the sun is not the same thing as gracefully handling an animation while the viewport size changes - the latter is much more challenging.

I agree, I was not even expecting it to handle the resize well. I just thought the landing page wanted me to resize my window to test responsiveness (before I noticed that the animation itself changes the content area size).

That being said, when resizing a window, the scrollbar should not reset/jump to top. At the very least, it should revert to what it was when going back to full size.