Visible scroll bar code not working

I opened a prior ticket regarding my staging website. I needed a scroll bar, and the code you supplied worked great. https://ww.wp.xz.cn/support/topic/add-visible-scroll-bar/

For some reason, this same code placed in the custom css of the production site is not working. Can you figure out why that might be?

The password to the page is: password

The page I need help with: [log in to see the link]