How to reduce page scroll height?

Question

Telegram

There is a page, on it there are 4 blocks with different heights and absolute positioning superimposed on each other. 3 blocks are invisible (visibility: hidden), 1 is visible, visibility is changed by the script.
Due to the different heights of the blocks, an empty space appears at the bottom of the document.
The jquery.scrollbar scroll script is used.
It is necessary to decrease and increase the height of the page scroll by the script, for the correct display.

PS: using absolute positioning is vital.

Answer 1

When clicked, a callback request is sent, one of the parameters is the id of the message to which the keyboard is attached.
Use the editMessageText method ( https://core.telegram.org/bots/api#editmessagetext)) to change the message, not sendMessage

Answer 2

Instead of visibility: visible | hidden use display: block | none.
visibility: hidden does not hide the element from the output stream, it only hides it, i.e. it is still in the same place and occupies the same dimensions, only it does not display itself / its content.