How to remove the timeout when loading a page on Bootstrap?

Question

Bootstrap

Created a site (1 page), with the help of Mobirise this program uses Bootstrap.
What is the problem with the default parameters until the entire page (text and graphics) is loaded, the site page is not displayed and does not show the correct operation, during loading there is a white screen and that's it. Users get the impression that the site is down.
I tried to change the priority by changing .css in the file in some places. I did asynchronous loading, the result of all this is a curve loading page.
In which file and on which line can I change what would show that the site is at the loading stage?
Or tell me the working progress of the "bar" of this case, from the found (without refinement) the site loaded crookedly, or the bar itself did not work.

Answer 1

This is called a preloader) there are many ways on the net how to insert it on the site)
as an option - https://itchief.ru/lessons/javascript/preloader-fo...