Intro Section with Dropdown menu Challenge complete!

This is a FrontendMentor Javascript junior challenge. I'm having fun with those drop menu in javascript. Still having some trouble on how to use CSS animation in javascript, but I'm having progress. Though, I was trying to make the Sidebar slide off just like it slides in. I made the start Sidebar animation in CSS and was trying to make the end animation in javascript. Is that the correct way? I'd love to get some feedback on that or anything else. Thanks!