Could you please trust yourself? Seriously.
lewro.com
lewro.com
Native scrollbars. We have them. They're 25 years old. For the last decade or so, we've even had these handy scroll wheels that work with them. When you attempt to replace them with your cutesy home-rolled Javascript version and force me to navigate to a button and click it to scroll, you give me every incentive to ignore you.
See (e.g.) the classic Quiz Designed to Give You Fitts: