<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://kit.fontawesome.com/a91a27e46f.js" crossorigin="anonymous"></script>
<div class="container">
<center><h2>JQuery Full Screen Search Box</h2></center>
<div class="col-12">
<div class="search-bar">
<a href="javascript:;"><i class="fa fa-search"></i></a></i>
</div>
<div class="search-area">
<span class="closebtn">×</span>
<div class="search-field">
<form action="">
<input type="text" placeholder="Search.." name="search">
<button type="submit"><i class="fa fa-search"></i></button>
</form>
</div>
</div>
</div>
</div>