small jquery issue - animation works when closing hamburger nav, but not opening

So I'm developing a Shopify right now over [here]([login to view URL]) (password is jeolyu - you'll need it to see the page) but I'm having issue with a jQuery animation. You can test the issue out yourself by opening & closing the hamburger nav in the upper right hand corner of the page. Notice that when opening the nav, there is no animation - it's just kinda suddenly open. However clicking the icon again (it turns into an 'x' while open) you'll see that it has this animation where it kind of gracefully shrinks away. I'm not an expert in jQuery so I think this may be something small I'm missing... If you can give me a fix to try out without needing to log in that would be ideal. I think even the right CSS property might be able to correct this. If you absolutely need back end access for this, let me know, but I'll be definitely be prioritizing any freelancer that doesn't need that.