How do I add this Parallax Effect to a Gallery?

Hey all!

I have this codepen that I think is really cool to show previous projects on my website https://codepen.io/thomassaulay/pen/XWJdORa

(currently I have a similar layout on my home page with a portfolio section but the images are static).

However when I use this codepen and refresh the website it doesn't create that parallax effect I'm looking for. 

Could someone help me achieve it? I have also put the css code in <style></style> and JS in <script> </script>

https://khaki-bumblebee-rgm8.squarespace.com/&nbsp;

website is live - no pass 

Thanks! 

Squarespace - Codepen HTML uses a different HTML format, so to make code work, first you need to change your Squarespace section HTML, same as this format. If you can't do this, you can use Code Block > Copy - paste all code in HTML box

Next add code in CSS box to Custom CSS

With code in JS box, you need to use this code

<script src="https://cdnjs.cloudflare.com/ajax/libs/rellax/1.10.0/rellax.min.js"></script>
<script>
  // var scene = document.getElementById('hover-parallax');
// var parallaxInstance = new Parallax(scene);
// parallaxInstance.friction(0.8, 0.8);

// Parallax on scroll. From -10 to +10.
var rellax = new Rellax('.rellax');



</script>