Check out example codes for "how to get a division to be in centre of screen in responsive web page for screen of any size". It will help you in understanding the concepts better.

Code Example 1

<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">

<div class="d-flex justify-content-center align-items-center bg-secondary w-100" style="height: 300px;">

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