<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet" integrity="sha384-wvfXpqpZZVQGK6TAh5PVlGOfQNHSoD2xbE+QkPxCAFlNEevoEH3Sl0sibVcOQVnN" crossorigin="anonymous">
<nav class="navbar navbar-expand-md navbar-dark bg-dark">
<div class="container">
<a class="navbar-brand" href="index.html">Simple Ecommerce</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarsExampleDefault" aria-controls="navbarsExampleDefault" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse justify-content-end" id="navbarsExampleDefault">
<ul class="navbar-nav m-auto">
<li class="nav-item">
<a class="nav-link" href="index.html">Home</a>
</li>
<li class="nav-item active">
<a class="nav-link" href="category.html">Categories <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="product.html">Product</a>
</li>
<li class="nav-item">
<a class="nav-link" href="cart.html">Cart</a>
</li>
<li class="nav-item">
<a class="nav-link" href="contact.html">Contact</a>
</li>
</ul>
<form class="form-inline my-2 my-lg-0">
<div class="input-group input-group-sm">
<input type="text" class="form-control" aria-label="Small" aria-describedby="inputGroup-sizing-sm" placeholder="Search...">
<div class="input-group-append">
<button type="button" class="btn btn-secondary btn-number">