How to make smooth loading of elements on the page?

Question

css

Here's how on this site for example voiceplace.com/individual-training

Answer 1

There seems to be no loading, but just an animation when scrolling.
If yes, then here is video one , and video two .

Answer 2

readymag

Answer 3

where is the download? There is no ajax request when scrolling. They are just blocks that appear. We cling to the scroll event, determine which elements are visible, add a class, in css we hang animation on this class.
There are a million ready-made solutions, for example https://daneden.github.io/animate.css/