Problem with dropdown bootstrap not showing up properly - html

Question

The items of the dropdown menu are not displaying properly.What should I do ? The website is working good on the mobile phone(the nav part) but on the pc it's crappy. Code:
<nav class="navbar navbar-inverse">
<div class="container-fluid">
<div class="navbar-header">
<button type="button" id="butonuldinnav" 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>
</div>
<div class="collapse navbar-collapse" id="myNavbar">
<ul class="nav navbar-nav">
<li class="dropdown">
<a class="dropdown-toggle" data-toggle="dropdown" href="#">A
<span class="caret"></span></a>
<ul class="dropdown-menu">
<li>B</li>
<li>C</li>
</ul>
<li>X</li>
<li>Y</li>
</ul>
</div>
</div>
</nav>
ORDER
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script src="//netdna.bootstrapcdn.com/bootstrap/3.1.1/js/bootstrap.min.js"></script>
<link rel="stylesheet" type="text/css" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
<link rel="stylesheet" href="{% static 'styles.css' %}">
Images :
problem
if I scroll down

Answer 1

Try:
<nav class="navbar-inverse navbar-nav navbar-header">
<div id="butonuldinnav" data-bs-toggle="collapse" data-bs-target="#myNavbar">
<i class="fa fa-bars"></i>
</div>
<ul class="collapse navbar-nav" id="myNavbar">
<li><a class="dropdown-toggle" href="#" data-bs-toggle='collapse' aria-expanded='false' data-bs-target='#A'>
A <i class="caret"></i></a>
<ul id='A' class="collapse">
<li>sub-1</li>
<li>sub-2</li>
</ul>
</li>
<li>B</li>
<li>C</li>
</ul>
</nav>
Links and script:
<link href='https://bootstrap.min.css' rel='stylesheet' />
<script src='https://bootstrap.bundle.min.js'/>
<link href="https://font-awesome.min.css" rel="stylesheet"/>