What’s “best” practice for navigation menu?

I am in the process of cleaning up my categories of blog posts. I’d like to use these in a category based menu system. I’ve about 28 categories that will be broken down into two main groups: Articles & Book. The Resources page is a separate item for the same menu.

In the past, I’ve had problems with drop down menus. They work fine on the desktop version of my site: https://www.inspiration-point.org However, they don’t stay down or not accessible on a tablet. Yet, On my smartphone, the menu is fine.

I’m using the Masonry Brick theme (child). Any suggestions?