Why doesn't the div have 100% width and height if I set it?

Question

css

I wrote that the div was in the center of the site. For the body, I set min high 100 in. and to the div 100% width and height, but anyway the div has a height proportional to its content.

Answer 1

https://yandex.ru/search/?text=css%20100%25%20height
https://habr.com/ru/post/189252/
38 minutes waiting for an answer here, instead of instantly getting it in a search engine.