Check out example codes for "how to make a division center css". It will help you in understanding the concepts better.

Code Example 1

position:absolute;
top:50%;
left:50%;
transform:translate(-50%,-50%);

Code Example 2

<div id="outer">
  <div id="inner">Foo foo</div>
</div>
//css:, demo with border
<style>
#inner {
  display: table;
  margin: 0 auto;
  border: 1px solid black;
}

#outer {
  border: 1px solid red;
  width:100%
}
</style>

Code Example 3

margin:auto

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