How to change color of scroll bar in Aspire?

I saw an earlier thread that mentioned to change the code in the Customize > Additional CSS in order to do this.
However, this is the only code I have in the Additional CSS:

/* GeneratePress Site CSS */ .inner-pages-header h1 {
font-size: 60px;
font-weight: 600;
} /* End GeneratePress Site CSS */

It doesn’t look like that controls the scroll bar … or does it. I want to change the color of mine as well.
Thanks.