I am doing a navigation bar with bootstrap of type collapse for when it is seen in mobiles, but when I decrease the size of the page in the browser I get only 3 icon lines from the menu but it does not show it when I click this is the code that I have from the page
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="description" content="Portfolio freeCodeCamp tutorials">
<meta name="author" content="">
<link rel="stylesheet" href="custom.css">
<!-- bootstrap links -->
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet" integrity="sha384-wvfXpqpZZVQGK6TAh5PVlGOfQNHSoD2xbE+QkPxCAFlNEevoEH3Sl0sibVcOQVnN" crossorigin="anonymous">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<title>ejemplo portfolio</title>
</head>
<body data-spy="scroll" data-target=".navbar"><!-- offset ? -->
<nav class="navbar navbar-inverse navbar-fixed-top" role="navigation">
<div class="container-fluid">
<div class="navbar-header">
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#mynavbar">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a id="logo" class="navbar-brand" href="#">Malditagaseosa</a>
</div>
<div class="collapse navbar-collapse" id="mynavbar">
<ul class="nav navbar-nav">
<li><a href="#about">About</a></li>
<li><a href="#portfolio">Projects</a></li>
<li><a href="#contact">Contact</a></li>
</ul>
<ul id="social" class="nav navbar-nav navbar-right">
<li><a href="www.github.com"><i class="fa fa-github"></i></a></li>
<li><a href="www.facebook.com"><i class="fa fa-facebook"></i></a></li>
<li><a href="www.instagram.com"><i class="fa fa-instagram"></i></a></li>
</ul>
</div>
</div>
</nav>
</body>