Having trouble importing background from CodePen

Hi, I’m having a hard time figuring out why my code isn’t showing up right on my front end. I’m wanting to add this as a background to my website https://codepen.io/undeadcreature/pen/PoyWJpB.

Here is the code that I’m putting into a code box, which is nested inside a container #particles-js:


#particles-js { position: absolute; width: 100%; height: 100%; background-color: rgb(161, 12, 12); background-size: cover;
    background-position: 50% 50%;

I’m sure it’s something simple but I cannot figure out why I can’t get this code to run?