Parent and child page display in menu

I’m struggling as to the best display of my child pages and how the drop downs look. My www.remarpro.com site pushes my whole page down when I hover over to see the other pages. It is not good.

I’m looking at my old Chateau theme site on wordpress.com and it is doing exactly what I want as far as showing the child pages in the menu. Example:
https://www.aneternalimpact.com (don’t like) vs.
https://aneternalimpact.wordpress.com (like)

Questions:
1. Is there a way to get the wordpress.com CSS and see what the differences are? I can’t find it.
2. Is there a better, cooler way to display the menu pages I don’t even know about?

Thanks!
Jon