Links aren't clickable after using parallax scrolling - html

Question

I've been making this website for school and I thought i'd figure out how parallax scrolling works. So i've started with the simpelest tutorial to be precise this one. After doing this I placed my navigation bar in. I remember this worked fine at the time but after working allot on the responsiveness I didn't check back and now I can't click on the links anymore.
This is my html:
<div id="group2" class="parallax_group">
<!-- <div class="parallax_layer parallax_layer-back">
background
</div> -->
<div class="parallax_layer parallax_layer-base">
<div id="nav" class="nav">
<ul>
<li><a class="active" href="#">Home</a></li>
<li>Over ons</li>
<li>Wat leveren wij?</li>
<li>Contact</li>
<li>Demo</li>
</ul>
</div>
<div class="section group">
<div class="col span_1_of_3">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Quibusdam id nam, necessitatibus at odit nobis vitae, dolor sequi sunt doloremque minima, debitis. Sed debitis possimus esse soluta mollitia est culpa.</p>
</div>
<div id="middle" class="col span_1_of_3">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Qui autem impedit, a, error accusantium soluta molestias quidem quo totam beatae eligendi sint, modi voluptatem nemo fugiat recusandae ullam consequatur nihil?</p>
</div>
<div class="col span_1_of_3">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Provident voluptatibus, quaerat nostrum ullam distinctio praesentium! Nemo eveniet provident id, tenetur cumque natus, quas porro possimus maiores, minus amet laboriosam ea?</p>
</div>
</div>
</div>
</div>
And this is my css:
* {
padding: 0;
margin: 0;
}
body {
text-align: center;
}
h1{
display: inline-block;
font-family: 'Raleway', sans-serif;
color: white;
text-shadow: -1px 0 black, 0 1px black, 1px 0 black, 0 -1px black;
}
p{
display: inline-block;
font-family: 'Raleway', sans-serif;
color: black;
}
header {
z-index: 5;
line-height: 100vh;
}
header .parallax_layer-back {
background: url(sample.jpg);
background-size: contain;
background-repeat: no-repeat;
}
#group2 {
z-index: 3;
}
#group2 .parallax_layer-base {
background-color: #dbdbdb;
}
.parallax {
perspective: 300px;
height: 100vh;
overflow-x: hidden;
overflow-y: auto;
}
.parallax_layer {
position: absolute;
top: 0;
right: 0;
bottom: 0;
left: 0;
}
.parallax_layer-base {
transform: translateZ(0px);
z-index: 4;
}
.parallax_layer-back {
transform: translateZ(-300px) scale(2);
z-index: 3;
height: 150vh;
}
.parallax_layer-deep{
transform: translateZ(-600px) scale(3);
z-index: 2;
background-color: #dbdbdb;
}
.parallax_group {
position: relative;
height: 100vh;
transform-style: preserve-3d;
/*transform: translate3d(700px, 0, -800px) rotateY(30deg);*/
}
/*Columns*/
/* SECTIONS */
.section {
clear: both;
padding: 0px;
margin: 0px;
}
/* COLUMN SETUP */
.col {
display: block;
float:left;
margin: 1% 0 1% 1.6%;
}
.col:first-child { margin-left: 0; }
/* GROUPING */
.group:before,
.group:after {
content:"";
display:table;
}
.group:after {
clear:both;
}
.group {
zoom:1; /* For IE 6/7 */
}
/* GRID OF THREE */
.span_3_of_3 {
width: 100%;
}
.span_2_of_3 {
width: 66.1%;
}
.span_1_of_3 {
width: 32.2%;
}
#middle{
border-top: 0px;
border-bottom: 0px;
border-right: 1px;
border-left: 1px;
border-style: solid;
}
/*navigation*/
.nav {
position: sticky;
top: 0px;
height: 100px;
width: 100%;
z-index: 30;
font-family: 'Raleway', sans-serif;
font-size: 20px;
background-color: #dbdbdb;
}
.nav ul {
list-style-type: none;
margin-left: 0;
padding-top: 40px;
font-size: 25px;
font-family: 'Raleway', sans-serif;
line-height: 0;
z-index: 30;
}
.nav li {
display: inline-block;
margin-left: 15px;
padding-bottom: 25px;
z-index: 30;
}
a:link {
color: #2F649B;
font-family: inherit;
}
a:visited {
color: #2F649B;
}
a:hover {
color: #6D92B9;
text-decoration: none;
}
a:active {
color: #26507C;
text-decoration: none;
}
footer {
position: sticky;
bottom: 0px;
height: 100px !important;
line-height: 100px;
width: 100%;
}
I know it's allot of code but I have no idea what it could be so i went and gone ahead and gave you everything.
edit: The other html parallax group:
<!DOCTYPE html>
<html>
<head>
<title>Squirel WebDesign</title>
<link rel="stylesheet" type="text/css" href="main.css">
<link rel="stylesheet" type="text/css" href="handheld.css" media="screen and (max-device-width: 480px), screen and (max-width: 480px)">
</head>
<body>
<div class="parallax">
<header class="parallax_group">
<div class="parallax_layer parallax_layer-base">
<h1>i'm a bloody big header preferably with a squirel</h1>
</div>
<div class="parallax_layer parallax_layer-back">
</div>
<div class="parallax_layer parallax_layer-deep">
</div>
</header>