Vertical Align Center with Bootstrap Modal 4.3 - css

Question

I'm trying to align vertically in the center of my modal in the body and nothing is happening. What is happening? I use version 4.3 of bootstrap.!
<section>
<div id="search-shopkeeper-modal" class="modal fade" tabindex="-1" role="dialog" aria-labelledby="shopkeeperModal" aria-hidden="true">
<div class="modal-dialog modal-xl" role="document">
<div class="modal-content">
<div class="modal-header border-0 p-0 m-0">
<div class="container-fluid p-2">
<form action="">
<div class="form-row">
<div class="col-12">
<div class="input-group input-group-lg">
<div class="input-group-prepend">
<span id="search-shopkeeper-addon" class="input-group-text bg-transparent border-0"><i class="fas fa-search"></i></span>
</div>
<input type="text" class="form-control rounded-0 border-0 shadow-none" placeholder="Digite o nome do Lojista..." aria-label="Username" aria-describedby="search-shopkeeper-addon">
</div>
</div>
</div>
</form>
</div>
</div>
<div class="modal-body" style="border: 1px red solid">
<!-- #todo -->
<div class="container d-flex align-items-center" style="border: 1px red solid">
<div><h1 class="text-center">SEM RESULTADOS!</h1></div>
</div>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default text-white shadow-none" data-dismiss="modal" style="background-color: #333333 !important">Fechar</button>
</div>
</div>
</div>
</div>
</section>

Answer 1

You want to add the following rules:
.modal-body {
display: flex;
align-items: center;
justify-content: center;
}
This can be seen in the following:
.modal-content {
height: 500px; /* Needed for this example to demonstrate the change */
}
.modal-body {
display: flex;
align-items: center;
justify-content: center;
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
<section>
<div id="search-shopkeeper-modal" class="" tabindex="-1" role="dialog" aria-labelledby="shopkeeperModal" aria-hidden="true">
<div class="modal-dialog modal-xl" role="document">
<div class="modal-content">
<div class="modal-header border-0 p-0 m-0">
<div class="container-fluid p-2">
<form action="">
<div class="form-row">
<div class="col-12">
<div class="input-group input-group-lg">
<div class="input-group-prepend">
<span id="search-shopkeeper-addon" class="input-group-text bg-transparent border-0"><i class="fas fa-search"></i></span>
</div>
<input type="text" class="form-control rounded-0 border-0 shadow-none" placeholder="Digite o nome do Lojista..." aria-label="Username" aria-describedby="search-shopkeeper-addon">
</div>
</div>
</div>
</form>
</div>
</div>
<div class="modal-body" style="border: 1px red solid">
<!-- #todo -->
<div class="container d-flex align-items-center" style="border: 1px red solid">
<div>
<h1 class="text-center">SEM RESULTADOS!</h1>
</div>
</div>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default text-white shadow-none" data-dismiss="modal" style="background-color: #333333 !important">Fechar</button>
</div>
</div>
</div>
</div>
</section>

Answer 2

Just add "d-flex align-items-center" classes to modal-body
p.s this is an option to use bootstrap but you can do it via css like in comment above
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" rel="stylesheet"/>
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#search-shopkeeper-modal">
Launch demo modal
</button>
<section>
<div id="search-shopkeeper-modal" class="modal fade" tabindex="-1" role="dialog" aria-labelledby="shopkeeperModal" aria-hidden="true">
<div class="modal-dialog modal-xl" role="document">
<div class="modal-content">
<div class="modal-header border-0 p-0 m-0">
<div class="container-fluid p-2">
<form action="">
<div class="form-row">
<div class="col-12">
<div class="input-group input-group-lg">
<div class="input-group-prepend">
<span id="search-shopkeeper-addon" class="input-group-text bg-transparent border-0"><i class="fas fa-search"></i></span>
</div>
<input type="text" class="form-control rounded-0 border-0 shadow-none" placeholder="Digite o nome do Lojista..." aria-label="Username" aria-describedby="search-shopkeeper-addon">
</div>
</div>
</div>
</form>
</div>
</div>
<div class="modal-body d-flex align-items-center" style="border: 1px red solid; height: 500px;">
<!-- #todo -->
<div class="container d-flex align-items-center" style="border: 1px red solid">
<div><h1 class="text-center">SEM RESULTADOS!</h1></div>
</div>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default text-white shadow-none" data-dismiss="modal" style="background-color: #333333 !important">Fechar</button>
</div>
</div>
</div>
</div>
</section>