How do I create a slide down a navigation bar on scroll?

Learn how to slide down a navigation bar on scroll with CSS and JavaScript

You can read on how to do it in this link: https://www.w3schools.com/howto/howto_js_navbar_slide.asp

Try it yourself here: https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_navbar_slide