How to make a sticky navbar?

I'm trying to make some code to make a sticky navbar, such that the position is fixed when I scroll down, however, it doesn't work. I wonder if the CSS is the problem, because most of the HTML and javascript would not really affect it. I have tried it on some of my other websites, and they work, but it doesn't seem to work on this one.

<div id="main-nav">
    <nav>
        <h2 id="logo" class="main-nav">Captain Max from ERA</h2>
        <br>
        <ul class="main-nav">
            <li> <a href="#">Listings</a></li>
            <li> <a href="#">Get in touch</a></li>
            <li> <a href="#">Projects</a></li>
        </ul>
    </nav>
</div>

The script for this is here, I'm not sure if anything is wrong with this though.

<script>
var navbar = document.getElementById("main-nav");
var sticky = navbar.offsetTop;
function myFunction() {
    if (window.pageYOffset >= sticky) {
        navbar.classList.add("sticky")
    } else {
        navbar.classList.remove("sticky");
    }
</script>

The CSS is here, it seems like I made a property that altered how the sticky keyboard works.

.sticky {
  position: fixed;
  top: 0;
  width: 100%
}

.sticky + .content {
  padding-top: 60px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
    html {
    font-family: 'Raleway', sans-serif;
    font-size: 20px;
    font-weight: 300;
    text-rendering: optimizeLegibility;
}

nav {
    background-color: #7b8195;
    color: #e9e6df;
    overflow: hidden;
}

#logo {
    font-family: 'Raleway', sans-serif;
    font-size: 250%;
    border-top: 10px;
    padding-right: 150px;
    padding-left: 10px;
    padding-top: 10px;
}

nav li {
    display:inline-block;
    margin-left: 40px;
}

.main-nav {
    float: left;
    list-style: none;
    margin-right: 60px;
    border-bottom: 10px;
    padding-bottom: 10px;
}

.main-nav li a {
    float: right;
    color: #e9e6df;
    text-decoration: none;
    font-size: 90%;
}

.main-nav li a:link,
.main-nav li a:visited{
    padding-bottom: 8px;
    color: #e9e6df;
    text-decoration: none;
    font-size: 90%;
    border-bottom: 2px solid transparent;
    transition: border-bottom 0.2s;
}

.main-nav li a:hover,
.main-nav li a:active{
   border-bottom: 2px solid #e9e6df;
}

The link to the website is here

Solution

What I can see here in your website is you havn't closed the script properly. You have missed one closed } brases.

<script>
var navbar = document.getElementById("main-nav");
var sticky = navbar.offsetTop;
function myFunction() {
    if (window.pageYOffset >= sticky) {
        navbar.classList.add("sticky")
    } else {
        navbar.classList.remove("sticky");
    }
   }

</script>