<title>Bootstrap Example</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="/css/bootstrap/bootstrap3.3.7.min.css">
<script src="/js/bootstrap/jquery.min.js"></script>
<script src="/js/bootstrap/bootstrap3.3.7.min.js"></script>
#section1 {padding-top:50px;height:500px;color: #fff; background-color: #1E88E5;}
#section2 {padding-top:50px;height:500px;color: #fff; background-color: #673ab7;}
#section3 {padding-top:50px;height:500px;color: #fff; background-color: #ff9800;}
#section41 {padding-top:50px;height:500px;color: #fff; background-color: #00bcd4;}
#section42 {padding-top:50px;height:500px;color: #fff; background-color: #009688;}
<body data-spy="scroll" data-target=".navbar" data-offset="50">
<nav class="navbar navbar-inverse navbar-fixed-top">
<div class="container-fluid">