JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<form id="search" action="/search">
<div class="input-group">
  <input type="search" class="form-control" name="q" placeholder="Zoek in de site" aria-label="Search">
  <div class="input-group-append">
<span class="btn"><i class="fa fa-search"></i></span>  </div>
</div>
</form>

CSS

#search .btn {
  padding-right: 1rem;
  padding-left: 1rem;
  border: 1px solid #ced4da;
}

#search span.btn {
  cursor: auto;
}