How should I make the height to be responsive?

Question

Right sidebar's height is fixed with px. How should I make it's height to be as much as it's on the left side? Without tables, flexbox, bootstrap or js?
https://code.sololearn.com/Woyf3NyZOqN2/?ref=app

Answer 1

To make the sidebar take up as much space as the height of the screen, set it's height to 100vh

#sidebar{
height:100vh;
}

Answer 2

Finally I used height in px both parts. But it doesn't look as good as it should, when I rotate my phone 90°. Empty space appears bottom

Answer 3

Empty space solved by adding padding to the #main2

Answer 4

Tryed 100vh and result wasn't right. It became longer than it had been with 100% property but shorter than the left side was.

Answer 5

Give a height in %

Answer 6

It doesn't work