Why does the container follow the indoor unit?

Question

css

If wrapper is set to margin: -100px 0 0 0, then the content block will move with it. This is according to what layout laws?)

<div class="content">
<div class="wrapper">
</div>
</div>

Answer 1

This is according to what layout laws?)

According to the laws of collapse of vertical margins.
Further, it is easy to google what it is, how it behaves and ways to get rid of it.

Answer 2

What did you decide? Please provide an example code.
Here is the code confirming that there is no such effect - https://codepen.io/aliencash/pen/ExVgWJz?editors=1100С