Simple Dropdown MAIN MENU

Hi, I'm new here. 

Looking for a way to have my main menu be a collapsable dropdown menu.

I don't want subfolder menus, I'm just looking to have the small number of pages in my menu be tidied away: start collapsed, and appear when the menu icon is clicked. 

This used to be a simple option one could choose in earlier square space sites, but the new sites don't seem to allow this.

Does anyone have any ideas on how I could achieve this? Thank you.