Bootstrap: add margin between columns - html

Question

I'm trying to put extra margin space between columns on my Bootstrap grid layout.
I've tried adding custom CSS class like this
.classWithPad {
margin: 10px;
padding: 10px;
}
but didn't solve my problem, also I've tried adding ml-1 and mr-1 but I didn't get desired. Here is my code:
When I tried to add some extra margin/padding the corresponding column is moved to a new row.
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap#4.6.1/dist/css/bootstrap.min.css" integrity="sha384-zCbKRCUGaJDkqS1kPbPd7TveP5iyJE0EjAuZQTgFLD2ylzuqKfdKlfG/eSrtxUkn" crossorigin="anonymous">
<div class="row mt-4 justify-content-between">
<div class="col-md-4 card border-radius-15 bg-shadow pt-3">
<h5>General Information</h5>
<hr/>
<div class="row">
<div class="col-md-6 pr-0">
paragraphs...
</div>
<div class="col-md-6 pl-0 text-right">
paragraphs...
</div>
</div>
</div>
<div class="col-md-4 card border-radius-15 bg-shadow pt-3">
<h5>Features</h5>
<hr/>
<div class="row">
<div class="col-md-6 pr-0">
</div>
<div class="col-md-6 pl-0 text-right">
</div>
</div>
</div>
<div class="col-md-4 card border-radius-15 bg-shadow pt-3">
<h5>Game Manufacturers</h5>
<hr/>
<div class="row">
<div class="col-md-6 pr-0">
</div>
<div class="col-md-6 pl-0 text-right">
</div>
</div>
</div>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap#4.6.1/dist/js/bootstrap.bundle.min.js" integrity="sha384-fQybjgWLrvvRgtW6bFlB7jaZrFsaBXjsOMm/tB9LTS58ONXgqbR9W8oWht/amnpF" crossorigin="anonymous"></script>

Answer 1

You generally don't want to mix structural and presentation elements. In this case, you've combined columns with cards. Put the cards inside the columns, and if you wanted them full-height you can use h-100 on them.
That, along with the container that should be present around outer rows, and you're all good. If you want more spacing, use px-* classes on the columns.
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap#4.6.1/dist/css/bootstrap.min.css" integrity="sha384-zCbKRCUGaJDkqS1kPbPd7TveP5iyJE0EjAuZQTgFLD2ylzuqKfdKlfG/eSrtxUkn" crossorigin="anonymous">
<div class="container-fluid">
<div class="row mt-4 justify-content-between">
<div class="col-4">
<div class="card h-100 border-radius-15 bg-shadow pt-3">
<h5>General Information</h5>
<hr/>
<div class="row">
<div class="col-md-6 pr-0">
<p>paragraphs...</p>
</div>
<div class="col-md-6 pl-0 text-right">
<p>paragraphs...</p>
</div>
</div>
</div>
</div>
<div class="col-4">
<div class="card h-100 border-radius-15 bg-shadow pt-3">
<h5>Features</h5>
<hr/>
<div class="row">
<div class="col-md-6 pr-0">
<p>paragraphs...</p>
</div>
<div class="col-md-6 pl-0 text-right">
<p>paragraphs...</p>
</div>
</div>
</div>
</div>
<div class="col-4">
<div class="card h-100 border-radius-15 bg-shadow pt-3">
<h5>Game Manufacturers</h5>
<hr/>
<div class="row">
<div class="col-md-6 pr-0">
<p>paragraphs...</p>
</div>
<div class="col-md-6 pl-0 text-right">
<p>paragraphs...</p>
</div>
</div>
</div>
</div>
</div>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap#4.6.1/dist/js/bootstrap.bundle.min.js" integrity="sha384-fQybjgWLrvvRgtW6bFlB7jaZrFsaBXjsOMm/tB9LTS58ONXgqbR9W8oWht/amnpF" crossorigin="anonymous"></script>