How to implement partial covering of the 1st block by the second one when scrolling?

Question

PHP

Hello colleagues. Interested in your opinion on how to create the effect link to the gif (click on the top right on the three dots - open the original). First, the top of the second block fits on the 1st. Then, at a certain point, the effect stops working and the standard scrolling follows. How did you solve this problem in your practice?

Answer 1

$newArray = array_merge(...$array);

Answer 2

In JS, you can do this by setting different styles for boxes when scrolling the page.
This article can help you link .