<div class="container">
<div class="jumbotron">
<div class="row">
<div class="col-xs-12">
<h1 class="text-center-xs">Joseph Santoni</h1>
</div>
</div>
</div>
</div>
The text is not centring at all.
<div class="container">
<div class="jumbotron">
<div class="row">
<div class="col-xs-12">
<h1 class="text-center-xs">Joseph Santoni</h1>
</div>
</div>
</div>
</div>
The text is not centring at all.
This is Bootstrap 3 syntax, not BS4.
I suggest review the docs on what classes you can use for BS3 or BS4.