How to create a hoverable dropdown bar with categories?

I am interested to know if it is possible to create a comprehensive drop-down bar with sub-categories using Squarespace's templates for either 7.0 or 7.1. An example of what I'm trying to achieve would be Squarespaces own drop-down (see picture)

This is a custom megamenu, built by a professional developer using Squarespace 7.0 Developer Mode. There isn't a built in feature that can do this, but several snippets of code are available that would allow you to build something similar.