Safari 8.0 fullscreen menu issue

I have built a concept site, linked below. In my testing on Browserstack I have noticed that the hamburger menu does not work in in Safari 8.0 and below. The menu icon when clicked simply does not open the menu itself. The issue does not exist in any other modern browsers I have tested on.

Preview link
Live site link

I have tried to debug this but have found it a little difficult due to Webflow adding that additional layer of abstraction from the code. Would anyone be able to speculate what might be causing this as I’m at a bit of a loss as it stands!

Many thanks