Hamburger menu not working on mobile, need help with functionality of Collections intro pages

[Rweedn]

Hello! Greetings from Switzerland. I need help with fixing the non-working hamburger menu on the mobile format. Plus I am happy to engage someone to assist me in creating separate Collection title pages as I need to highlight each Collection as a separate entity. any help?   

https://travelaire-press.myshopify.com/