center div horizontally bootstrap code example

Example 1: bootstrap 4 center div

<div class="d-flex justify-content-start">...</div>
<div class="d-flex justify-content-end">...</div>
<div class="d-flex justify-content-center">...</div>
<div class="d-flex justify-content-between">...</div>
<div class="d-flex justify-content-around">...</div>

Example 2: bootstrap center button horizontally

<button type="submit" class="btn btn-primary mx-auto d-block">Submit</button>