How to set block height to viewport height?

Question

css

Hey!
I have two problems:
1) UIKit 3 has .uk-height-viewport- https://asuikit.com/v3/height
I apply it like this:

<div class="uk-width-1-2 uk-overflow-auto uk-height-viewport">

But you can do it like this:

<div class="uk-width-1-2 uk-overflow-auto" uk-height-viewport>

The second option doesn't work at all.
In CSS I did this (replaced 100vh with 90vh):

.uk-height-viewport {
  max-height: 90vh;
}

And then a dilemma arose, 100 vh - went below the viewport resolution , and 90 - just right. But only for my monitor (1920x1080).
How can I make the width adaptive to the entire viewport (for me it is probably +- 980 px. In other words, the window where the entire site is placed)?
2) I made a grid via uk-grid :

<div class="uk-flex-center" uk-grid>
  <div class="uk-width-1-2 uk-overflow-auto uk-height-viewport">

Here is a screenshot-layout:

According to the standard, these two blocks go in the center:
The left block goes a little to the left, and the right one - a little to the right. But I would like exactly the same as in the screenshot: the left block goes strictly in the center, and the right block goes to the right of the central one. How to do this? Double grid?

Answer 1

I throw off a couple of examples as an answer to item 2, but I think here is the solution to item 1 at the same time, for which I did not see the code.
Option one:
..
second nested.
to understand the first line and the essence was taken from the question itself
..
The width of the blocks can be changed. there should be no questions