Creating an "Above The Fold

I am trying to create a section with a specific width and height to act as "above the fold".

The width should be 1536 px and the height 864 px.
The width I am placing it in the theme customizer, in the section where it says DESIGN / CONTAINER / CONTAINER WIDTH. There I place the 1536 px.

And the height I am placing it in the Guttemberg editor options, in the SECTION options, in SPACING / MINIMUM HEIGHT.

The problem is that it generates a blank space at the bottom of the section that I don't understand why it appears.

Does anyone know why it happens and how can I solve it?

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