<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="../../maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
<script src="../../ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js"></script>
<script src="../../cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
<script src="../../maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
<style>
body {
position: relative;
}
</style>
</head>
<body data-spy="scroll" data-target=".navbar" data-offset="50">
<nav class="navbar navbar-expand-sm bg-dark navbar-dark fixed-top">
<ul class="navbar-nav">
<li class="nav-item">
<a class="nav-link" href="#section1">Section 1</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#section2">Section 2</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#section3">Section 3</a>