Consider adjusting the positioning of your side navbar to fixed.
nav {
position: fixed;
z-index: 1;
background-color: white;
}
Here is a functional demonstration:
nav
{
position:fixed;
width: 100px
height: 200px;
top: 0;
left: 0;
background-color: white;
}
nav ul
{
position: absolute;
height: 200px;
top: 50%;
}
.content
{
margin: 30px 220px;
background-color:red;
}
<!DOCTYPE html>
<html>
<head>
<title>Sidebar fixed</title>
<meta charset="utf-8" />
</head>
<body>
<nav>
<ul>
<li><a href="#">Item 1</a></li>
<li><a href="#">Item 2</a></li>
<li><a href="#">Item 3</a></li>
</ul>
</nav>
<div class="content">
<p>
Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. nonumy eirmod tempor invidunt...
</p>
</div>
</body>
</html>